Preheat the oven to 425°F (220°C). Line a baking sheet with parchment paper.
In a large bowl, whisk together the flour, baking powder, sugar, baking soda, and salt.
Add the cold butter cubes to the flour mixture. Using a pastry cutter or your fingers, cut the butter into the flour until the mixture resembles coarse crumbs with some pea-sized pieces.
Pour in the cold buttermilk and stir gently with a wooden spoon until just combined. Do not overmix; the dough should be slightly sticky.
Turn the dough out onto a lightly floured surface. Gently fold the dough over itself 3-4 times to create layers, then pat it into a 1-inch thick rectangle.
Using a 3-inch biscuit cutter, cut out 12 biscuits. Place them on the prepared baking sheet, spacing them slightly apart.
Bake the biscuits for 12-15 minutes, or until golden brown on top. Remove from the oven and let cool completely on a wire rack.
While the biscuits bake, whisk together the eggs, milk, salt, and pepper in a medium bowl.
Heat a non-stick skillet over medium-low heat. Pour in the egg mixture and cook gently, stirring occasionally, until the eggs are softly scrambled and just set. Remove from heat.
To assemble the sandwiches, slice each biscuit in half horizontally. Place a cooked sausage patty on the bottom half, followed by a slice of cheddar cheese and a portion of scrambled eggs. Top with the biscuit halves.
Wrap each sandwich tightly in plastic wrap or aluminum foil. Place the wrapped sandwiches in a freezer-safe container or zip-top bag.
To reheat, remove the wrapping and microwave the sandwich on a microwave-safe plate for 1-2 minutes, or until heated through. Alternatively, reheat in a 350°F (175°C) oven for 15-20 minutes, wrapped in foil.