Broccolini-Cheddar Gratin With Rye Breadcrumbs

Preparation

1. Step 1

   Pulse bread and two chiles in a food processor until coarse crumbs form (make them about the size of chickpeas or smaller). You should have about 1½ cups. Transfer breadcrumbs to a small bowl. Toss with 2 Tbsp. oil; season with salt and pepper.

   Step 2

   Heat a medium skillet over medium and toast breadcrumb mixture, stirring often, until browned and crisp, about 5 minutes; remove from heat.

   Step 3

   Preheat oven to 425°. Toss broccolini on a rimmed baking sheet with remaining 2 Tbsp. oil; season with salt and pepper. Roast, tossing occasionally, until tender and bright green, 5–8 minutes. Let cool slightly. Transfer broccolini to a medium bowl and toss with 2 Tbsp. Parmesan and remaining 2 chiles; season with salt and pepper.

   Step 4

   Place half of broccolini in a 2-qt. baking dish and top with half of cheddar. Add remaining broccolini and finish with remaining cheddar. Scatter breadcrumbs over and sprinkle with remaining 2 Tbsp. Parmesan. Bake until breadcrumbs are browned and cheese is melted, 10–15 minutes.

   Step 5

   DO AHEAD: Breadcrumbs can be made 2 days ahead; store tightly wrapped at room temperature. Gratin can be assembled 6 hours ahead; cover and chill. Bake just before serving.