In the bowl of a stand up mixer with the paddle attachment beat together the butter, icing sugar and vanilla until light and fluffy, approximately 3-4 minutes.
Add the flour and mix just until combined. Move the dough to a lightly floured flat surface and gently knead to form a smooth ball.
Divide the dough into 24 balls and place each ball in a lightly greased and floured mini muffin pan cup. Flatten the ball with a lightly floured shot glass (or the utensil shown in the photo) so that it covers the bottom and the sides. Refrigerate for 30-60 minutes.
Pre-heat oven to 325F (160C).
Fill each cup with a teaspoon or two of filling, bake for about 20-25 minutes or until lightly golden. Remove and top each cup with more of the filling. Let cool for about 10 minutes then move to a wire rack. Enjoy!
In a small bowl combine the toffee bits and mini chocolate chips.
To remove the cups, gently run the tip of a knife around the edges to loosen. Depending on your oven temperature you may want to start checking at about 15 minutes.