Before getting ready to mix your dough, feed your starter. Do this by mixing warm water, instant potato flakes, and sugar and pouring it into your starter. Allow your starter to feed for 8–24 hours prior to mixing your dough to ensure that you have an active sourdough starter.

In the bowl of a stand mixer, add all the dough ingredients except the butter. Using the dough hook attachment, mix on medium speed until the dough starts to pull away from the sides of the bowl.

Cover the bowl with plastic wrap or beeswax wrap and let the dough rest for 10 minutes. This resting period allows the flour to fully hydrate and makes kneading easier.

After the dough has rested, remove the wrap and knead in the softened butter by hand. Keep kneading until the butter is fully absorbed into the dough.

Cover the bowl again and let the dough rise in a warm spot until it doubles in size, about 8 to 10 hours.

Preheat your oven to 350°F.

After the first rise, prepare the filling. In a skillet over medium heat, cook the ground sausage until browned and fully cooked through. Add the cream cheese to the hot sausage and stir until melted and combined. Set aside.

Grease a 9x13 baking dish. Transfer the risen dough to the dish and gently press it out to fit the bottom of the pan, making an even layer across the base. You can lightly flour your hands if needed to help with sticking.

Spread the sausage and cream cheese mixture evenly over the dough.

Pour the egg mixture evenly over the top.

Bake for 25–30 minutes at 350°F, or until the eggs are set and the top is lightly golden.

Let the casserole rest for a few minutes before slicing and serving.