Prepare your 90-second bread according to instructions. Set it aside to cool.
Slice the tomato and mozzarella. Slice the bread in half to create two thin slices. Place the tomatoes on the bottom slice, then add the cheese, then spread the pesto on the top slice before placing it on top of the sandwich,
Melt the butter in a grill pan over medium heat. Place the sandwich in the pan, pesto side down, and press it down with a spatula as it cooks. In approximately 3 minutes, or once the cheese begins to melt, carefully flip it and repeat on the other side. Cut on the diagonal and serve immediately.
Macros per serving: 520 calories, 7 grams net carbs, 20 grams protein, 45 grams fat.