Croissant Sausage Brunch Bake with Gruyère Step-by-step instructions

Before you start

Before starting, take the croissants out of the fridge if they were stored there, and let them come to room temperature. If you're using day-old croissants, tear them into bite-size pieces and set aside. Brown the sausage in a skillet over medium heat until fully cooked, then transfer to a plate.

In the same skillet, melt butter and cook the sliced leeks slowly until soft and caramelized. This can be done ahead of time and refrigerated. Whisk together the eggs, milk, and Dijon mustard in a large bowl, and have the shredded Gruyère measured and ready. Preheat the oven to 185°C (365°F) when you're ready to bake.

Instructions

Prep and Layer

1. 1Prepare the Fillings
   Heat a large skillet over medium heat. Add the sage pork sausage and cook, breaking it into small pieces, until browned and cooked through, about 8 minutes. Transfer to a plate. In the same skillet, melt a tablespoon of butter and add the sliced leeks. Cook slowly, stirring occasionally, until soft and caramelized, about 10 minutes. Set aside.
   Look for The sausage is browned and the leeks are golden and tender.
   Safe temperature 160°F (71°C) internal temperature (ground meat)
   Tip Use day-old croissants for better absorption.
2. 2Layer the Croissants
   Tear the croissants into bite-size pieces and spread them evenly in a buttered 9x13-inch baking dish. Scatter the browned sausage and caramelized leeks over the croissants, then sprinkle with half of the shredded Gruyère.
   Look for The dish is evenly layered with croissants, sausage, leeks, and cheese.
   Tip Press the croissants down gently so they soak up the custard.

At the end of this phase, you have a baking dish filled with torn croissants, browned sausage, caramelized leeks, and a sprinkle of Gruyère. The sausage should be fully cooked and the leeks soft and golden. The croissants should be evenly distributed so every bite gets a bit of filling. The kitchen smells of butter and sage, and the leeks are sweet and tender. Before moving on, make sure the custard is whisked until smooth and the remaining cheese is ready to sprinkle.

Custard and Soak

3. 3Make the Custard
   In a large bowl, whisk together the eggs, whole milk, and Dijon mustard until completely smooth and well combined. Season with a pinch of salt and black pepper.
   Look for The custard is pale yellow and frothy.
   Tip Whisk thoroughly to ensure the mustard is fully incorporated.
4. 4Pour and Top
   Pour the custard evenly over the croissant mixture, making sure all pieces are soaked. Sprinkle the remaining Gruyère over the top. Let the dish sit at room temperature for 10 minutes so the croissants absorb the custard.
   Look for The croissants are saturated and the top is covered with cheese.
   Tip Press down lightly on the croissants to help them soak.

The custard is poured over the croissants, and the dish sits for 10 minutes. The croissants are absorbing the egg and milk mixture, and the top is sprinkled with the remaining Gruyère. The custard should be evenly distributed, with no dry spots.

The dish looks creamy and inviting, with the cheese just beginning to melt. The croissants are soft but not falling apart, and the leeks and sausage are visible throughout. The wait is worth it, as this soak ensures a tender, custardy interior.

Bake and Rest

5. 5Bake Until Golden
   Preheat the oven to 185°C (365°F). Bake the strata for 28 minutes, or until the top is deeply golden and the custard is set. The internal temperature of the eggs should reach 160°F (71°C).
   Look for The top is golden and crisp, and the center is set.
   Safe temperature 160°F (71°C) internal temperature (egg dishes)
   Tip If the top browns too quickly, cover loosely with foil.
6. 6Rest and Serve
   Remove the bake from the oven and let it rest for 5 minutes before serving. This allows the custard to settle and makes slicing easier. Serve warm, with extra Gruyère if desired.
   Look for The bake is puffed and golden, with a slight jiggle in the center.
   Tip Letting it rest prevents it from falling apart.

After 28 minutes in the oven, the bake is golden and puffed, with a crisp, bubbly top. The cheese is melted and browned in spots, and the edges are caramelized. A knife inserted in the center comes out clean, and the internal temperature reads 160°F (71°C). The kitchen smells of toasted butter and Gruyère. Let it rest for 5 minutes, then cut into squares. The layers are visible: crisp croissant tips, savory sausage, sweet leeks, and creamy custard.

Common mistakes

One common mistake is using fresh croissants, which can become soggy and fall apart. Always use day-old or stale croissants, or dry them out in the oven briefly. Another is not cooking the sausage thoroughly before layering, which can lead to undercooked meat. Take the time to brown it well.

Overcrowding the baking dish can also prevent the custard from setting properly; make sure the croissants are in a single layer and not packed too tightly. Finally, don't skip the resting time after baking, as it helps the strata hold its shape when sliced.

How to tell it’s done

The croissant bake is done when the top is deeply golden brown and the custard is set in the center. To check, insert a knife or a skewer into the middle; it should come out clean, without any wet custard clinging to it. The internal temperature of the eggs should reach 160°F (71°C) for food safety.

If the top is browning too quickly but the center is still soft, cover the dish loosely with foil and continue baking. Let the bake rest for 5 minutes before serving; this allows the custard to settle and makes it easier to cut into neat squares.

• Ground meat: 160°F (71°C) in the thickest part
• Egg dishes: 160°F (71°C) in the thickest part
• Steaks, chops and roasts: 145°F (63°C) in the thickest part, then a 3-minute rest