Preheat oven to 375 degrees. Coat a 7x11 inch baking dish with nonstick spray and place on a baking sheet.

Brown the sausage in a saute pan over medium heat, breaking into chunks. Transfer cooked sausage to a paper towel lined plate and set aside. Reserve the drippings for the sage gravy.

Whisk together eggs, 1 1/4 cups milk, cream, salt, and black pepper in a large measuring cup; set aside.

Layer biscuits bottoms in prepared baking dish. Spinkle half the sausage over the biscuits and top with half the cheddar cheese. Repeat layering (except for the cheddar). Pour the egg mixture over top, transfer to over and bake for 30 minutes. Sprinkle remaining cheddar cheese over top of casserole and bake until eggs are set (center is no longer jiggly and instant read thermometer registers 165 degrees), a toothpick inserted into a biscuit comes out clean, and tops are golden (about 10-15 minutes more). Let casserole stand for 10 minutes.

For the sage gravy - melt butter in the sausage drippings in a saute pan over medium heat. Whisk in the flour until smooth; cook two minutes. Clolwy whisk in two cups of milk until mixture is smooth. Cook gravy until slighly thickened (about 5-8 minutes). Stir in sage and pepper flakes. Season gravy with salt and pepper.