Preheat oven to 300F degrees. Line one baking sheet with parchment paper.
In a large bowl, combine all of the crumble ingredients. Use your hands to mix the ingredients together until they form a crumbly dough.
⅔ Cup Gluten Free 1-to-1 Flour Blend, ½ Cup Sugar, 2 Tablespoon Light Brown Sugar, 2 Tablespoon Rainbow Sprinkles, ½ teaspoon Baking Powder, ½ teaspoon Salt, ¼ Cup Vegan Butter, 1 teaspoon Vanilla
Sprinkle the dough onto the prepared baking sheet, breaking it into various size clumps.
Bake for 12 minutes, flipping halfway through.
Remove from oven and cool completely on the baking sheet. They will continue to get more crunchy as they cool.
For the cake
Once the crumbles are done baking, raise your oven temperature to 350F degrees.
Grease a 13x9 inch pan and line the bottom with parchment paper.
Sift together the flour, arrowroot powder, baking powder and salt. Set aside.
1 ¾ Cup Gluten Free 1-to-1 Flour Blend, 2 Tablespoon Arrowroot Powder, 2 teaspoon Baking Powder, ½ teaspoon Salt
In the bowl of an electric mixer combine the butter, oil and sugar. Beat on medium speed for 3 minutes until light and fluffy. Scrape down the bowl.
⅓ Cup Vegan Butter, ⅓ Cup Olive Oil, 1 ¼ Cup Sugar
Add the vanilla.
1 ½ teaspoon Vanilla
Add the eggs one at a time beating for 30 seconds in between each addition. Scrape down the bowl. Turn the mixer to medium speed and beat for 4 minutes. The mixture should become very fluffy.
3 Eggs
Turn your mixer to the lowest setting. Add half of your flour mixture, followed by half of the milk. Repeat with the remaining flour and milk. Mix just until combined. Scrape down the bowl to ensure all ingredients have been incorporated.
⅔ Cup Non-Dairy Milk
Remove the bowl from the mixer and add the rainbow sprinkles. Fold them in by hand, taking care not to over-mix and break the sprinkles (it will cause the colors to bleed when baked).
⅓ Cup Rainbow Sprinkles
Pour the batter into the prepared pan. Let rest for 10 minutes before baking.
Bake for 32-35 minutes in preheated oven. The cake is done when the top springs back when gently poked near the middle and the sides are beginning to pull away from the pan.
Remove from oven and cool in the pan for 10 minutes. Then turn out onto a wire rack to cool completely.
For the milk soak
Combine milk and vanilla in a small bowl. Set aside until ready to assemble cake.
¼ Cup Non-Dairy Milk, 1 teaspoon Vanilla
For the frosting
Combine vegan butter and cream cheese in the bowl of an electric mixer. Beat for 2-3 minutes until smooth. Scrape down the bowl.
½ Cup Vegan Butter, 4 ounces Vegan Cream Cheese
Add the vanilla, salt, lemon juice and powdered sugar. Mix slowly at first until the dry ingredients are incorporated. Then turn your mixer to high speed and beat for 5 minutes until fluffy.
2 teaspoon Vanilla, 1 ¼ Cup Powdered Sugar, ½ teaspoon Salt, ½ teaspoon Lemon Juice
To assemble the cake
Place cooled cake on a piece of parchment paper
Use a 6-inch pastry ring to cut 2 full circles and 2 half circles out of the rectangular cake.
Place your pastry ring on a serving plate. Use a piece of acetate to create a cake collar inside the ring. The acetate should stick up higher than the ring.
First place the 2 half circles in the bottom of the pastry ring. This will be your bottom later. Use cake scraps to fill in any gaps in the center. Ensure that the layer is flat.
Using a pastry brush, soak the first layer of cake with a little more than 1 tablespoon of the vanilla milk soak.
Add 3 tablespoon of frosting on top of the cake layer and spread to the edge of the cake.
Sprinkle the crunchy crumbles on top of the frosting, making an even layer. Press them down gently with your hand to settle them in the frosting.
Add another 3 tablespoon of frosting on top of the crumbles. Again, spread it to the edge of the cake.
Repeat the steps with the second layer of cake - cake, milk soak, frosting, crumbles, then more frosting.
For the final layer, place the cake in the ring.
Brush with the milk soak.
Top with all of the remaining frosting and sprinkle with the remaining crumbles.
Refrigerate or freeze the cake inside of the cake collar to set the icing. Once set, you can remove the acetate.
Notes
Storage: Store leftover cake in an airtight container in the refrigerator for 3-4 days.