Preheat the oven to 375ºF. Line a baking dish with parchment paper, or use the olive oil to grease it well.
Heat 1 Tbsp of olive oil in a pan over medium heat. Add the diced potatoes and sauté until they begin to soften & get some golden color, about 5 to 7 minutes. Transfer to the baking dish.
Add the vegetables (bell peppers, onion, garlic) to the pan and sauté until just softened, about 3 minutes. Transfer to the baking dish, over top of the potatoes.
Add the sausage to the pan, and cook until browned. Transfer to the baking dish.
To the baking dish, add the diced tomatoes. Stir the mixture of potatoes, vegetables, sausage, and tomatoes to combine.
In a large mixing bowl, whisk the eggs with milk and spices. Pour over top of the meat & vegetable mixture.
Transfer to the oven and bake for 30 to 35 minutes, or until the eggs are fully set.
Slice into 8 servings, and serve hot over arugula or your choice of greens.