Step 1

• Adjust rack to middle position (middle and top positions for 12 servings) and preheat oven to 400 degrees. Wash and dry produce. Coat a 9-by-13-inch baking dish (two 9-by-13-inch baking dishes for 12) with nonstick cooking spray. • Dice brioche into 1/2-inch pieces. • Cut prosciutto into 11/2-inch pieces. Roughly chop parsley.

Step 2

• In a large bowl, whisk together eggs*, cream sauce base, mustard, nutmeg, and half the cheddar until combined. • Add brioche pieces to egg mixture and toss until fully coated. Set aside and allow to soak until ready to use in Step 4.

Step 3

• Halve, peel, and thinly slice onion. • Heat a large drizzle of oil in a large, preferably nonstick, pan over medium-high heat. Add onion and cook, stirring occasionally, until browned and softened, 8-10 minutes. • Add 1 tsp sugar (2 tsp for 12 servings) and a splash of water; cook, stirring, until onion is caramelized and jammy, 2-3 minutes more. Season with pepper.

Step 4

• Transfer strata mixture to prepared baking dish and spread out in an even layer. (For 12 servings, evenly divide mixture between two prepared baking dishes.) • Spread caramelized onion over strata. Evenly top with prosciutto pieces. TIP: Be sure to get the onion and prosciutto into all the nooks and crannies of the strata! • Sprinkle with remaining cheddar and a pinch of parsley.

Step 5

• Lightly coat a large piece of aluminum foil (two large pieces of foil for 12 servings) with nonstick cooking spray. Cover baking dish tightly with foil, coated side down. • Bake strata on middle rack until almost set, 20-25 minutes. (For 12, bake on top and middle racks, swapping rack positions halfway through.) • Once strata has baked 20-25 minutes, carefully remove and discard foil. Return to oven and continue to bake until cheese is browned, 10-12 minutes more. TIP: Don’t worry if your strata jiggles a bit! It will fully set as it cools.

Step 6

• Let strata cool for 5 minutes; cut into 6 pieces (12 pieces for 12 servings). • Divide between plates and sprinkle with remaining parsley. Serve. Wash hands and surfaces after handling raw eggs. Consuming raw or undercooked eggs may increase your risk of foodborne illness.