Preheat your oven to 400°F. While it heats, trim the asparagus and cut into 2-inch pieces, then mince the garlic cloves fresh (pre-minced garlic loses potency). Zest the lemon and chop the chives. This prep work takes just a few minutes and ensures everything is ready when you need it.

In a large bowl, combine the prepared asparagus with olive oil, minced garlic, salt, pepper, and red pepper flakes. Toss everything together until the asparagus is evenly coated with the oil and seasonings. This ensures every piece gets seasoned properly and the garlic distributes throughout for consistent flavor.

In a 9x13 inch baking dish, create three layers: spread 1/3 of the seasoned asparagus mixture as the first layer, then sprinkle 1/3 of the combined cheeses (mix cheddar and mozzarella together) over it. Repeat this layering process twice more, ending with cheese on top. I find mixing the cheeses together beforehand prevents uneven distribution and saves time during layering.

Place the casserole dish in the preheated 400°F oven and bake for 15 minutes, until the asparagus is tender-crisp and the cheese is melted and bubbling around the edges. The asparagus should still have some bite to it rather than becoming mushy.

Remove the casserole from the oven and immediately pour the warm, whisked hollandaise sauce evenly over the top layer of cheese. The heat from the casserole will keep the hollandaise warm and help it set slightly. Sprinkle the fresh chives and lemon zest over the top for brightness and color. Serve immediately while everything is hot and the hollandaise is still silky.