Ingredients
All-purpose flour
Unsalted butter
Granulated sugar
Eggs (room temperature)
Buttermilk
Clear or pure vanilla extract
Baking powder
Baking soda
Cornstarch (optional)
Rainbow jimmies sprinkles
Salt
For the frosting:
Butter and optional shortening
Powdered sugar
Vanilla extract
Milk or heavy cream
Instructions
1. Grease and line a 9×13 pan with parchment.
2. Cream butter and sugar for 2–3 minutes until pale and fluffy.
3. Add oil and vanilla extract; mix well.
4. Beat in eggs one at a time.
5. In a separate bowl, mix flour, baking powder, baking soda, salt, and cornstarch.
6. Add dry ingredients to the wet ingredients alternately with buttermilk.
7. Gently fold in rainbow jimmies sprinkles.
8. Spread the batter evenly into the prepared pan.
9. Bake at 350°F for 30–35 minutes.
10. Cool completely before frosting.
11. Frost with bakery-style vanilla frosting using an offset spatula.
Notes
Always use rainbow jimmies, not nonpareils, to avoid color bleeding.
Tent the cake with foil if it browns too fast.
Chill before slicing for cleaner cuts.
Store unfrosted at room temp for 24 hours, or refrigerate up to 5 days.
Can be frozen up to 2 months.
- Prep Time: 15 minutes
- Cook Time: 35 minutes
- Category: Dessert
- Method: Baking
- Cuisine: American
- Diet: Vegetarian
Nutrition
- Serving Size: 1 slice
- Calories: 410
- Sugar: 36g
- Sodium: 190mg
- Fat: 18g
- Saturated Fat: 11g
- Unsaturated Fat: 5g
- Trans Fat: 0g
- Carbohydrates: 56g
- Fiber: 1g
- Protein: 4g
- Cholesterol: 80mg