Preheat the oven to 180ºC and prepare a baking sheet with baking parchment. Whisk together the flour, baking soda, and salt in a small bowl and set aside. Cream the butter, vegetable baking fat, and sugar together until light. Then stir in the egg, lemon extract and sour cream. Mix the dry ingredients into the wet ingredients and combine to form a dough. Turn the dough onto a lightly floured surface and roll to 1/4 inch thick. Cut using a rounded edge cutter. Place each dough circle onto the baking sheet and bake for ten minutes or until the edges are just lightly browning. For the cream cheese topping, first mix together the cream cheese and soft butter until fully combined, then add the vanilla and icing sugar. Pipe the cream cheese into each cooled sugar cookie in a circular motion Due to the cream cheese, these sugar cookies must be kept refrigerated.