If you’re planning to bake this immediately, preheat the oven to 350ºf. if you’re prepping this the day before, no need to preheat now
In a large skillet, heat 2 tablespoons of butter over medium heat. Add leek and garlic and cook, stirring, until just starting to soften. Add asparagus, season with salt and pepper, and cook until crisp-tender, about 3-4 minutes. Toss in peas and spinach right at the end and give it a good stir and let cook another minute or two until spinach starts to wilt.
Combine the sourdough cubes and spring veggie mixture in a 9” x 13” casserole dish or something large enough to bake the mixture.
in a large bowl, whisk together the eggs, milk, cream, mustard, a large pinch of salt, and a bunch of turns of pepper. Pour into the dish on top of the sourdough mixture. top with crumbled goat cheese. cover with foil and bake immediately or refrigerate overnight or up to 24 hours.
bake (at 350fº) bake strata until egg is cooked through to center, about 35 minutes. Enjoy!