Tomato Tart

 Ingredients

• 
  
  4 tbsp. butter
• 2 whole large onions, halved and sliced thin

• Salt and pepper, to taste

• 2 whole store-bought pie crusts (or 1 good sized homemade crust)
• 1 1/2 c. grated fontina cheese (or monterey jack)
• 1/4 c. grated parmesan
• 1/4 c. grated gruyère (or swiss)
• 3 c. cherry tomatoes (yellow or red), washed and dried (plus more if needed)
• 1 whole egg
• 1/4 c. milk
• 16 whole basil leaves, chiffonade (more if needed)

Directions

• 1. Heat a large skillet over medium-low heat. Add the butter, onions, salt, and pepper and cook for 20 to 25 minutes, stirring occasionally, until the onions are soft and deep golden brown. Set aside.
  2. Preheat the oven to 450°.
  3. Smush both pie crusts into a ball, knead it around a bit to combine them, then roll it out into one large, thin crust. Lay onto a shallow quarter sheet pan, or cut in half and use 2 standard pie pans. Sprinkle on the cheeses in a single layer, then lay on the caramelized onions, then sprinkle the tomatoes over the cheese. 
  4. Mix together the egg and milk in a small bowl and brush it all over the crust around the edge of the tart. Bake the tart for 20 to 22 minutes, watching carefully to make sure the crust doesn't burn. (The tomatoes should be starting to burst apart, with some dark/roasted areas on the skin, and the crust should be deep golden brown.) If the crust is getting brown too fast, reduce the heat to 425°. 
  5. Remove the tart from the oven and allow it to sit for 5 minutes. Sprinkle the basil all over the top. Cut into squares and serve!  Marissa Carlson who gave me this recipe uses a buttermilk crust that is attached.  Recipe from The Pioneer Woman 

  Buttermilk Crust

   2 1/2 Cups Flour

  3/4 tsp salt

  1 Cup (2 sticks) butter - cold, cut into cubes 

  1/2 Cup cold buttermilk

  Directions:

  To make the crust, in a medium bowl, whisk together flour and salt.  Add cold, cubed butter and, using your fingers, work the butter into the flour mixture.  Quickly break the butter down into the flour mixture and some butter pieces will be the size of oak flakes, some will be the size of peas.  Create a well in the butter and flour mixture and pour in cold buttermilk.  Use a fork to bring the dough together.  Try to moisten all of the flour bits.  On a lightly floured work surface, dump out the dough mixture. It will be moist and shaggy.  That's perfect.  Divide the dough in two and gently knead into two disks.  Wrap each disk in plastic rap and refrigerate for 1 hour.