Melt the butter in a large skillet over medium heat. Add the chopped onion and cook for about 3–4 minutes until it softens and just begins to turn golden.
Toss in the broken tostadas or chips. Stir them around with the onions for a couple of minutes. They'll start to absorb the butter and soften.
Add the chopped cabbage and garlic. Season generously with salt and pepper. Continue cooking for 5 to 8 minutes, stirring occasionally, until the cabbage is sweet and tender
Stir in the chopped tomato and cook for just 2 to 3 minutes more.
Pour in the beaten eggs and gently scramble them with all the other ingredients until the eggs are just set and cooked through. Take the skillet off the heat immediately.
Stir in your Parmesan cheese. Serve the migas hot, with the rest of the Parmesan sprinkled generously over the top. Enjoy!