Preheat your oven to 350°F. While it heats, spray a 9x13-inch baking dish with cooking oil to prevent sticking. This gives you time to work on the sausage while the oven reaches temperature.

In a large pot over medium-high heat, brown the ground pork sausage, breaking it into small crumbles as it cooks, about 5-7 minutes. Once cooked through, transfer the sausage to your prepared baking dish. I like to leave some of the rendered fat in the pot—it adds rich flavor to the gravy. If there's excessive grease (more than 2 tablespoons pooled), pour some off carefully, but don't drain it completely.

Add the melted butter to the sausage drippings in your pot over medium heat. Once combined, whisk in the flour, salt, black pepper, and cayenne pepper, stirring constantly for 2-3 minutes until the mixture turns light brown. This roux is the foundation for a smooth, flavorful gravy, so don't skip the browning step—it adds depth that white flour won't give you.

Reduce heat to medium-low and gradually add the milk while whisking constantly to prevent lumps from forming. Add it in small portions—about 1/2 cup at a time—whisking until fully incorporated before adding more. Once all the milk is incorporated, continue stirring occasionally for 5-8 minutes until the gravy thickens enough to coat the back of a spoon. The gravy will continue to thicken slightly as it cools, so don't overdo it.

Pour the hot sausage gravy from Step 4 evenly over the cooked sausage in your baking dish. Open both cans of biscuits and cut each biscuit into quarters using a knife or kitchen shears. Scatter the biscuit pieces across the top of the gravy, nestling them slightly so they're partially submerged—this helps them stay moist while baking.

Place the casserole in your preheated 350°F oven and bake for 25-30 minutes, until the biscuit pieces are golden brown on top. The casserole should be bubbling around the edges. Remove from the oven and let it rest for 5 minutes before serving—this helps the gravy set slightly and makes it easier to portion.