Savory Croissant Skillet Pain Perdu with Asparagus & Prosciutto

Instructions

1. 1

   Preheat your oven to 400F (200C). In a large mixing bowl, whisk together 4 large eggs, 1 cup whole milk, 1 tbsp Dijon mustard, and 1/2 cup grated Gruyère (we save the rest for the crust). Season the custard with 1/2 tsp kosher salt and 1/4 tsp black pepper. Do not overmix; we want a cohesive liquid, not a frothy foam.

   5 min

   Tip: Have your custard ready before you start cooking. The skillet moves fast once it's on the stove.

2. 2

   Place a 10-inch cast-iron skillet over medium heat. Drop in 3 tbsp cultured butter. Let it melt, foam, and smell slightly nutty. Immediately toss in the 4 stale croissants, torn into chunks. Toast them in the hot butter, tossing occasionally, until the edges catch and turn deeply golden. This builds the foundational crunch.

   4 min

   Tip: Butter is not a garnish. The browned milk solids will give the bread a savory, nutty depth.

3. 3

   Push the toasted croissants slightly to the edges of the pan to expose the hot iron. Drop in the 1 bunch asparagus, cut into 2-inch pieces. Let them sizzle against the metal for just a couple of minutes until they turn bright green and get a slight blister. Turn off the heat completely.

   3 min

   Tip: Don't overcook the asparagus here; it will finish tenderizing in the oven.

4. 4

   Pour your prepared egg mixture evenly over the entire skillet. Gently press the croissant pieces down so they absorb the liquid but leave their top edges exposed to crisp. Drape the 3 oz sliced prosciutto gracefully over the top—do not bury it, we want the fat to render in the oven. Scatter the remaining 1/2 cup grated Gruyère over the exposed bread.

   2 min

   Tip: Leaving the prosciutto exposed is the secret to a shatteringly crisp, salty finish.

5. 5

   Transfer the skillet immediately to the hot oven. Bake until the edges pull away from the pan, the prosciutto is crispy, and the center has a gentle, confident wobble. We want lacy edges and a tender crumb, tight like a bad alibi is not the goal here.

   20 min

   Tip: Watch for the wobble. An overbaked custard weeps and turns rubbery.

6. 6

   Remove the skillet from the oven. Let time do the work: allow it to rest in the hot cast-iron for exactly 5 minutes before serving. The residual heat will gently set the center while preserving the moisture.

   5 min

   Tip: Don't skip this. Slicing immediately will result in a messy, weeping custard.