Preheat oven to 375 degrees F. Stir together flour, salt, baking powder, and baking soda in a medium bowl. Cube the cold unsalted butter and use your fingers to rub it into the flour mixture until it is in pea-sized pieces.
Stir in grated cheddar cheese so it is mixed well. Finally add in buttermilk and stir until just combined.
Turn the dough out onto a floured surface and fold it over itself a few times. Try not to overwork the dough. Use a biscuit cutter to cut out large round biscuits. You should get at least 8 and probably closer to 12 biscuits.
Move biscuits to a baking sheet lined with parchment paper and bake them at 375 degrees for about 30 minutes until they are golden brown.
For the Sausage:
Stir together all ingredients in a bowl. Portion out sausage into 8 even patties (about 2 ounces each).
Add patties to a large skillet over medium-high heat and cook for about 4-5 minutes per side until the sausages are well browned.
For the egg:
Scramble egg and pour into a nonstick pan or a pan with some oil or butter over medium heat. After about 90 seconds fold the egg over itself a few times so the egg is nice and light and cooked through.
For each sandwich:
Split a biscuit in half and add half of the cooked egg. Then top with sausage and serve while warm!
Storage:
If you want to freeze these, let them cool to room temperature and then wrap them well in foil. Freeze them and then store them in a freezer bag for up to 2-3 months. I prefer to reheat them in a 350 degree oven for 20-30 minutes so the biscuits don’t get soggy.