How to Make It
Preheat the oven to 400°. In a bowl, stir the cheese into the butter and spread on one side of each slice of bread.
In a medium bowl, combine the oil, lemon juice, garlic, olives and basil. In a food processor, pulse the zucchini until finely chopped. Fold the zucchini into the oil and lemon juice mixture and season with salt and pepper. Season the tomatoes with salt and pepper.
Arrange the bread on 2 large baking sheets, buttered side up. Bake the bread for 4 minutes, or until lightly toasted.
Set 6 slices of toast, buttered side up on a work surface. Top each with the frisée and the zucchini relish. Cover with another slice of bread, buttered side up and top with 2 slices of tomato and the remaining bread, buttered side down. Cut the sandwiches in half with a serrated knife and serve.