Preheat oven to 375.
Melt butter in a heavy-bottomed frying pan over medium-low heat.
Whisk eggs, mayonnaise, taco seasoning and salt; whisk until eggs turn a pale yellow color.
Pour eggs into prepared pan.
Using a spatula, push one edge of the egg toward the center of the pan, while tilting the pan to allow the liquid egg to flow in underneath. Repeat with the other edges, until there's no liquid left.
Remove from heat.
Place two tortillas, one on top of the other, in an 8-inch pie plate or in a cast iron skillet.
Spread 1/2 of the scrambled eggs on top of the tortillas.
Place 1/3 of the tomatoes on top of the eggs, and finish with a 1/3 of the cheese mixture.
Top with two tortillas and repeat, using the rest of the eggs, half of the tomatoes, and half of the cheese mixture.
Finish off with the last two tortillas, slices of tomatoes, and top with the rest of the cheese mixture.
Bake for 8 to 10 minutes, or until cheese is melted.
Cool for 5 minutes.
Cut and serve.