In a large frying pan cook the sausage links, browning on all sides. Remove to a paper towel-lined plate.
Drain off the grease and set the pan over medium heat.
Add the oil, roasted red peppers, onion and spinach. Season with a couple dashes of salt and pepper.
Cook, stirring often until the spinach is tender. Remove from heat.
Preheat the oven to 400 degrees F. Butter a 9x11-inch baking pan.
Slice the sausage into ¾-inch thick rounds. Spread them over the bottom of the baking pan.
In a large mixing bowl whisk the eggs and milk together with a couple good dashes of salt and pepper.
Stir the spinach mixture and cheese into the eggs. Slowly pour it over the sausage.
Bake until lightly golden around the edges and set in the middle 25 - 30 minutes.
Cut into squares for serving.