In a food processor, pulse together the filling ingredients; set aside.
Heat the oven to 350 degrees. Spray with baking spray a 10- or 12-cup Bundt pan, making sure to get into all the grooves of the pan.
In the bowl of your stand mixer, cream butter and 1 1/2 cups sugar until pale and fluffy using the paddle attachment (you could also beat it with a hand mixer), 4-5 minutes. Beat in the eggs one by one, waiting until each has been incorporated to add the next. Add the vanilla and mix to combine. Be sure to scrape the mixing bowl after each addition of the eggs.
In large bowl, whisk together the flour, cinnamon, baking powder, baking soda, salt and cinnamon; set aside.
Add half of the flour mixture to the mixer beat on low speed until incorporated. Scrape down the sides of the bowl to incorporate. Add in buttermilk and beat until incorporated followed by the remaining flour mixture; scrape the sides of the bowl to incorporate.
Spoon half of the cake batter into the Bundt pan; spread evenly with a spatula. Spoon the filling around the batter (make sure not to touch the edge pan). Spread on the rest of the batter evenly with a spatula. Tap the pan heavily on the counter a few times to help even out the batter and remove air pockets. Bake for 45-50 minutes, or until a toothpick inserted into the center of the cake comes out clean and the top springs back when lightly pressed.
Let the cake cool in the pan for 15 to 20 minutes, then flip the pan onto a cooling rack set inside a baking sheet. Tap the pan heavily onto the rack.
Mix 3 tablespoons water with the confectioners’ sugar. Separate into 3 small bowls.(You may need more confectioner’s sugar) Add a drop of each color food coloring and stir together. Add more water or confectioner’s sugar to achieve a spreadable consistency. Spread in alternating sections over the cake.
Cool cake completely before serving.