Preheat the oven to 350°F (175°C) if baking biscuits from scratch. Bake biscuits according to package or recipe instructions and let cool completely.
In a medium bowl, whisk together eggs, whole milk, salt, and black pepper until fully combined.
Heat a large nonstick skillet over medium heat and add butter. Once melted, pour in the egg mixture.
Cook eggs gently, stirring frequently, until softly scrambled and just set, about 4-5 minutes. Remove from heat.
Warm the cooked sausage patties in the skillet for 1-2 minutes until heated through.
Slice each biscuit in half horizontally.
Assemble each sandwich by layering scrambled eggs, one sausage patty, and one slice of cheddar cheese between the biscuit halves.
Wrap each sandwich tightly in plastic wrap or aluminum foil.
Place wrapped sandwiches in a large freezer-safe zip-top bag or airtight container and freeze for up to 3 months.
To reheat, unwrap a frozen sandwich and microwave on high for 1-2 minutes until heated through, or bake in a preheated 350°F (175°C) oven for 20-25 minutes.