Preheat your oven to 350°F (175°C). Grease and lightly flour a bundt pan using gluten-free flour, or spray the pan with non-stick cooking spray.

In a small bowl, mix the almond milk and apple cider vinegar. Let it sit for 5 minutes to create a dairy-free buttermilk substitute.

In a medium mixing bowl, whisk together the gluten-free flour, baking powder, baking soda, and salt.

In a large bowl, cream the dairy-free butter (or coconut oil) and granulated sugar until light and fluffy. Add the eggs one at a time, beating well after each addition. If using an egg substitute, add it here instead.

Mix in the vanilla extract and the dairy-free buttermilk mixture, alternating with the dry ingredients. Mix until just combined, being careful not to overmix.

Divide the batter into three equal portions. Leave one portion plain for the white layer, add red gel food coloring to one portion, and blue gel food coloring to the other portion. Stir each batter gently until the colors are evenly mixed.

Layer the colored batters into the prepared bundt pan. Start with the red batter, followed by the white batter, and finally the blue batter. For a marbled effect, use a skewer or knife to gently swirl the colors together.

Bake in the preheated oven for 45-50 minutes, or until a toothpick inserted into the center comes out clean.

Let the cake cool in the pan for 10 minutes, then carefully invert it onto a wire rack to cool completely.

Once cooled, frost the cake with dairy-free white frosting and decorate with sprinkles or edible glitter for a festive look.