Gluten Free Milk Bar Birthday Cake

Name: Gluten Free Milk Bar Birthday Cake
Prep time: 1 h 10 min
Cook time: 32 min
Total time: 1 h 42 min
Cuisine: American
Ingredients: 2/3 C Gluten Free 1-to-1 Flour Blend (I use Bob's Red Mill); 1/2 C Sugar; 2 Tbsp Light Brown Sugar; 2 Tbsp Rainbow Sprinkles; 1/2 tsp Baking Powder; 1/2 tsp Salt; 1/4 C Vegan Butter (melted); 1 tsp Vanilla; 1 3/4 C Gluten Free 1-to-1 Flour Blend (259 grams); 2 Tbsp Arrowroot Powder (or Cornstarch); 2 tsp Baking Powder; 1/3 C Vegan Butter (room temperature); 1/3 C Olive Oil; 1 1/4 C Sugar; 1 1/2 tsp Vanilla; 3 Eggs (room temperature); 2/3 C Non-Dairy Milk (room temperature); 1/3 C Rainbow Sprinkles; 1/4 C Non-Dairy Milk; 1/2 C Vegan Butter; 4 oz Vegan Cream Cheese; 2 tsp Vanilla; 1 1/4 C Powdered Sugar (sifted); 1/2 tsp Lemon Juice