In a medium bowl, add flour, baking soda, baking powder, cream of tartar and salt. Give that a quick mix to ensure everything is well incorporated.
Using a stand mixer with paddle attachment (or hand mixer), mix the butter, crisco, granulated sugar and powdered sugar on low/medium speed until light and fluffy. Add the egg and vanilla extract. Mix on low until everything is combined.
Slowly add the dry ingredients as you run the mixer on low. Add the sour cream and mix again until the dough comes together.
Divide the dough into 8 large cookies or 16 smaller cookies. Place cookies on a baking sheet lined with parchment paper. Press down on each ball to flatten and create a crater for the pudding. Chill in the fridge for at least 12 hours.
Preheat oven to 350. Bake cookies for 8-10 minutes for smaller cookies or 11-13 minutes for larger cookies until not greasy looking on top. Allow to cool.
For the pudding filling, mix the banana pudding and milk according to package instructions. Chill in the fridge.
For the whipped cream, mix heavy whipping cream and powdered sugar until soft peaks form. Add vanilla and mix for 10 more seconds.
Fold whipped cream into banana pudding. Spoon pudding mixture onto each cooled cookie, add banana slices and cookie crumbs, then top with more pudding and crumbs.