Here's a filling that should work nicely with cranberries. You may want to adjust sugar--the filling is tart, but you might like it sweeter. This recipe is enough for a 25 cm tart, about 3 cm deep. PREHEAT OVEN TO 180ºC . Whisk together eggs, sugar, zest and vanilla. Add the flour until well mixed. Set aside. In a small saucepan, heat the butter over high heat until foamy and brown. Pour the butter in a steady stream over the egg mixture, beating to incorporate. Add the cranberries and pour the mixture into your tart shell. Bake for 45 to 50 minutes. Let cool completely before serving.