For a crustless lemon tart, try baking the mixture in ramekins in a bain marie (water bath).
Lazy Mary's Lemon Tart
From the Food52 Cookbook by Amanda Hesser
Makes 1-9" tart, serves 8
For the filling:
1 large Meyer lemon, cut into 8 pieces, seeds removed
1 1/2 cups superfine sugar
8 tablespoons butter
1 tsp vanilla extract
4 large eggs
One 9" tart shell blind-baked*
Heat the oven to 350 degrees. Put the lemon, sugar, butter, vanilla and eggs into a food processor and process until smooth. Pour into the pre-baked pie shell. Bake for 30-40 minutes. (Watch during the last few minutes of baking so that the top does not burn.) Cool on a wire rack before serving.
* To blind bake a tart shell, line a 9" tart pan with pastry dough, prick the bottom with a fork all over, line it with 2 layers of aluminum foil and bake at 375 degrees for 10 minutes, remove the foil and bake another 10 minutes. Let it cool completely before filling.