Step 1: Preheat the oven to 350 degrees F.
Step 2: Grease and line your sheet pan.
Step 3: In a large mixing bowl, sift together the flour, sugar, baking soda, salt, and cocoa powder. In another large bowl, whisk together the oil, buttermilk, eggs, food coloring, vinegar, and vanilla.
Step 4: Using a standing mixer, mix the dry ingredients into the wet ingredients and combine until smooth.
Step 5: Place the batter in the prepared sheet pans. Bake, rotating the pan halfway through the cooking process, bake for about 30 minutes, until a toothpick inserted into the center comes out clean.
Step 6: Remove cake from the oven, invert the pan onto a cooling rack and let cool completely.
Step 7: Once cake has cooled, using a 2-inch round cookie cutter, cut out circles of the cake you baked. You will need 1 cake round for a 4oz (about 118.29 ml) mason Jar and 2 cake rounds for an 8oz (about 236.59 ml) mason jar.
Step 8: Spoon the cream cheese frosting into a piping bag and pipe frosting in the bottom of each jar add one cake round on top of the filling. Lastly, pipe another layer of cream cheese frosting onto the top of each cake.
Step 9: If using an 8 oz (about 236.59 ml) mason jar, repeat the process of adding another cake round and piping another layer of cream cheese frosting onto the top of each cake. You can also add sprinkles of your cake scraps as crumbles on top of your filling.
Step 10: At this time, your cake jar will be assembled and place your lid on top of the jar and seal it. Be sure not to overfill your jar so that it can close properly.
Step 11: Serve and enjoy!
