Divide the lean sausage into 4 equal portions and shape into patties slightly wider than your muffin (they'll shrink). Season both sides with a pinch of salt, pepper, and smoked paprika.
Heat a nonstick skillet over medium. Lightly oil. Cook patties 3–4 minutes per side until browned and cooked through (165°F). Transfer to a plate and tent with foil.
Whisk eggs, milk, salt, pepper, and garlic powder. Lightly oil an 8×8 baking dish or use a small nonstick skillet. Pour in the eggs. Cook low and slow on the stove (covered) until set, or bake at 350°F for 8–10 minutes. Lay cheese slices on top during the last minute to melt. Cut into 4 squares.
Split the whole-grain English muffins and toast until golden. For extra flavor, toast cut-side down in the sausage skillet to pick up those savory bits. Yes, science.
Bottom muffin, sausage patty, cheese-egg square, optional spinach or tomato, top muffin. Press gently.
If you want it extra gooey, return the assembled sandwich to the warm skillet for 30–60 seconds per side, covered.
Eat immediately, or let cool slightly for meal prep before wrapping.