Sweet Onion Tart Recipe

Prepare a tart pan by spraying it with cooking spray and arranging the pie crust in it. Tuck the ends along the edge. Bake for 10 minutes in a preheated 375 F. degree oven. Remove tart pan from oven and set aside. Do not turn off the oven.
In a large skillet melt 3 tablespoons of the butter with the olive oil. Sauté the onions on medium low until golden brown.
Drain the onions well on paper towels and allow to cool.
While the onions are cooling melt the remaining butter in a saucepan.
Add the flour, salt, and pepper. Whisk until the flour has become lightly golden brown.
Add ½ cup of milk to the saucepan and whisk until the flour and milk mixture is combined.
Add the remaining milk to the saucepan.
Bring to a boil and whisk until thickened.
Add 8 ounces of extra sharp cheddar cheese to the saucepan and whisk until the cheese has melted.
Arrange the cooked onions over the bottom of the pie crust. Pour the cheese sauce over the onions just until the onions are covered. Save or discard any remaining cheese sauce.
Sprinkle the rosemary over the top.
Spread the remaining cheddar cheese over the top of the tart.
Sprinkle the bread crumbs over the top of the cheese.
Bake in the preheated oven for 30 minutes or until the filling is bubbling and the top is a golden brown.
Allow to cool to room temperature before serving.