Melt the butter in a skillet over medium heat, and saute the leeks until tender. Spread evenly over the bottom of the pie crust.
In a bowl, toss together the Swiss cheese, Romano cheese, and flour. Spread over the leeks.
In a separate bowl, beat together the eggs and heavy cream. Pour over the cheese layer in the pie crust. Top with the tomato slices, and season with salt and pepper.
Bake 15 minutes in the preheated oven. Reduce heat to 325 degrees F (165 degrees C), and continue baking 30 minutes, until the crust is lightly browned and a knife inserted in the center of the quiche comes out clean.