• Preheat oven to 350° Grease and flour both of the Fillables cake pans. Set aside.

Make the cakes:

• In a large bowl, whisk together the flour, baking powder, baking soda, salt and nutmeg. Set aside.
• In the bowl of a stand mixer, blend together the 1 cup of butter and 1 ⅓ cups of granulated sugar on medium speed for 5 minutes until light and fluffy. Add in the sour cream and blend to combine. Add in the eggs one at a time, mixing well after each addition and then mix in the bourbon and vanilla.
• Add the flour mixture to the wet ingredients in two or three batches, mixing slowly after each batch until just combined.
• Pour ⅔ of the batter into the cake pan that has the indentations for the secret pockets. Pour the rest of the batter into the other prepared pan. Spread the batter in both pans into even layers.
• Bake both cakes for about 25 minutes: a tester inserted into the centers should come out clean. Place the pans on a cooling rack and allow them to cool completely: about an hour.
• Run a plastic knife carefully along the inside edge of the pans, then invert the pans to gently release the cakes.

Prepare the streusel and filling: 

• Chop the toasted pecans into small pieces. Set aside ½ cup of the chopped pecans; place the rest into a medium-sized bowl.
• Add in the ½ cup of brown sugar, ½ teaspoon of the cinnamon and ¼ cup of the melted butter. Stir to thoroughly combine the ingredients. Set this streusel aside: this will be used to fill the pockets in the cake.
• Use a hand or stand mixer to beat together the 1 ⅔ cups of confectioner's sugar, the remaining ½ teaspoon of cinnamon and the remaining ¼ cup of melted butter. Slowly add in the 1-2 tablespoons of milk until a thick, spreadable frosting forms. Stir in the remaining ½ cup of chopped pecans. Cover and set aside.

Assemble the cake:

• Place the bottom cake layer with the open pockets onto a serving platter. Fill all but one of the pockets with the brown sugar-pecan streusel, level with the top of the pocket. Into the last pocket place 1 teaspoon each of the green, purple and yellow decorating sugars.
• Add in the plastic baby or trinket so that it is below the edge of the pocket. To keep track of which pocket has the baby, stick a toothpick into the outside of the cake to mark it. 
• Spread the bottom of the second cake layer with the pecan frosting, spreading it all the way to and a bit over the edges of the cake layer. Place this frosting side down over the pocket layer, so that the frosting covers the pockets. Line up the cake edges so that they align, and very gently press the top layer down so the the frosting peeks out between the layers.
• Pour the glaze over the top, completely covering it. Smooth it with a rubber spatula and push it towards the edges of the cake so that it can drip down the sides. Let the glazed cake sit for about 10 minutes before adding the decor.
• Spoon the green, purple and yellow sparkling sugars onto the top of the cake: you can do stripes of colors or a pinwheel design of colors widening out from the center. Leave white glaze peeking out from between the colors or have the colors bands touching each other: you can really do it up any way you want!
• When it's time to serve the cake, remove the toothpick marking the location: if you want, use it to scratch the side of the cake so you will know where the baby is located. Cut the slices down through the center of each petal or rounded-out edge. This way, the filling of each slice will be visible on both sides of the slice. You will be able to see who gets the slice with the baby or trinket, as it tumbles out in a wave of purple, green and yellow sugar!