**Preheat and Prepare Pans:** Preheat the oven to 350°F (175°C). Grease two 8-inch round cake pans and line the bottoms with parchment paper.

**Mix Dry Ingredients:** In a medium bowl, whisk together flour, sugar, baking powder, baking soda, and salt.

**Prepare Wet Mixture:** In a large bowl, beat butter and oil until smooth. Add eggs one at a time, mixing well. Stir in buttermilk, vanilla, and vinegar.

**Add Food Coloring:** Mix in purple gel food coloring a little at a time until the desired shade is achieved.

**Combine Mixtures:** Gradually add the dry ingredients to the wet mixture, stirring until just combined. Avoid overmixing.

**Bake:** Divide batter evenly between the prepared pans. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean.

**Cool:** Allow cakes to cool in the pans for 10 minutes, then transfer to a wire rack to cool completely.

**Make Frosting:** In a large bowl, beat cream cheese and butter until smooth. Gradually add powdered sugar, vanilla, and a pinch of salt. Beat until fluffy.

**Assemble Cake:** Place one cake layer on a serving plate. Spread frosting on top, then place the second layer over it. Frost the top and sides evenly.

**Decorate and Serve:** Garnish with sprinkles or edible glitter for a finishing touch. Slice and enjoy!