To prepare a nutty treacle tart, you'll first need to prepare the ingredients for the tart. Preheat the oven to 375 degrees F (190 degrees C) and grease and flour two tart shells. Place the sugar, butter, eggs, and vanilla into the saucepan and bring to the boil. Cook the mixture over medium heat, whisking constantly, until thickened, about 5 minutes. Remove from the heat and stir in the flour, baking powder, cinnamon, nutmeg and salt. Pour the batter into ungreased tartshells and bake for 20 minutes or until the top is golden brown. Allow to cool before serving.