In a bowl, whisk together the eggs, salt and pepper. Set aside.
In the deep half of a frittata pan over medium heat, melt the butter with 1 1/2 tsp. of the oil. Add the macaroni, ham and peas and cook, stirring occasionally, until heated through, about 2 minutes. Using a spatula, flatten the mixture and spread it evenly across the pan. Cook, without stirring, until a golden crust forms underneath, 5 to 6 minutes. Sprinkle the cheese on top and let melt for 1 minute.
Meanwhile, in the shallow half of the frittata pan over medium-low heat, warm the remaining 1 tsp. oil. Pour the eggs over the macaroni in the deep pan. Place the shallow pan upside down on top of the deep pan and cook until the edges of the frittata are set and the center is beginning to set, about 4 minutes. Uncover the pan and gently run the spatula around the edge of the frittata to loosen the sides. Re-cover with the shallow pan and flip the frittata into the shallow pan. Cook, covered, until the eggs are set, 2 to 4 minutes.
Carefully slide the frittata onto a serving plate and let rest for 3 to 5 minutes before slicing. Serves 8.