Preheat oven to 375F. Line a shallow pie plate with parchment paper and brush with olive oil. Layer sheets of filo sheets (about 10-15, for reference) in the pie plate.

Spoon and spread half of the mustard on the bottom of the filo pastry. Add a handful of the cheese, then layer the tomato slices on top. Repeat one more time. Top with remaining cheese, season with salt and pepper and toasted sesame seeds.

Bake in the oven about 25-30 minutes until the pastry is crisp, the cheese is melted, and the tomatoes are cooked but still hold their shape.