In a mixing bowl, whisk together the flour, baking powder, baking soda, salt, cinnamon, ginger, nutmeg, and allspice until combined; set aside.

In the bowl of a stand mixer fitted with a paddle attachment, beat the butter and brown sugar together on medium speed until lightened and creamy. Beat in the eggs, one at a time, until combined, scraping down the sides and bottom of the bowl as needed. Beat in the Greek yogurt, molasses, maple syrup, and vanilla on medium speed.

With the mixer on low speed, slowly pour the dry ingredients into the wet ingredients. Mix until just combined, scraping down the sides and bottom of the bowl as needed.

Fill cupcake liners 2/3 of the way full. Bake for 19-21 minutes or until a toothpick inserted in the center comes out clean or with few crumbs attached. Allow to cool in the pan for 5 minutes before transferring to a wire rack to cool completely.

In the bowl of a stand mixer fitted with a paddle attachment beat the butter, shortening, and salt together until smooth and creamy. Add 2 cups of powdered sugar and beat until smooth.

Add the caramel sauce along with the remaining 2 cups of powdered sugar, and beat until lightened and fluffy. Add additional caramel sauce if needed to get the right consistency.

Frost or pipe buttercream onto cupcakes, as desired. Garnish with Twix bars and sprinkles. Cupcakes keep well covered tightly at room temperature or in the refrigerator for up to 5 days.