Step 1: Make the Flour and Milk Base
- Combine Milk and Flour: In a small saucepan, whisk together the milk and flour until smooth and no lumps remain.
- Cook the Mixture: Place the saucepan over medium heat and cook, whisking constantly, until the mixture thickens to a pudding-like consistency. This usually takes about 5–7 minutes. You’ll know it’s ready when the mixture coats the back of a spoon.
- Add Pumpkin: Once the mixture has thickened, add in the pumpkin puree and continue to cook for an additional 2–3 minutes. The pumpkin will add flavor and moisture to the buttercream.
- Cool Completely: Remove the pan from the heat and transfer the mixture to a bowl. Cover it with plastic wrap, pressing it directly onto the surface to prevent a skin from forming. Allow it to cool completely to room temperature before using it in the frosting. You can speed this up by placing it in the fridge, but don’t let it get too cold.
Step 2: Cream the Butter and Sugar
- Cream the Butter: In a mixing bowl, beat the softened butter on medium-high speed for 3–4 minutes, until it’s light and fluffy.
- Add Sugar Gradually: With the mixer on low, slowly add the granulated sugar. Once it’s all added, increase the mixer speed to medium-high and beat for another 5–6 minutes, until the sugar is well incorporated and the mixture looks creamy.
Step 3: Combine Everything
- Add the Pumpkin Base: When the flour-pumpkin mixture has fully cooled, add it to the butter mixture, a spoonful at a time, mixing well after each addition. Continue beating on medium-high speed for another 3–4 minutes, until the frosting is fluffy and smooth.
- Flavor with Spices and Vanilla: Add the pumpkin pie spice, vanilla extract, and a pinch of salt. Mix until all the flavors are well blended, and the buttercream has a creamy consistency.
Tips for the Perfect Pumpkin Spice Buttercream
- Cooling the Flour Base: Make sure the cooked flour mixture is fully cooled before adding it to the butter. If it’s even slightly warm, it could melt the butter, and the frosting won’t set properly.
- Taste and Adjust Spices: Taste your frosting as you go, and adjust the pumpkin pie spice if you’d like a stronger or subtler spice flavor.
- Chill Time: If your buttercream feels a bit too soft after mixing, you can pop it in the fridge for about 10 minutes to firm it up before piping or spreading.
Storage
Store any leftover buttercream in an airtight container in the refrigerator for up to 5 days. Bring it to room temperature and give it a quick whip with the mixer before using again.
Enjoy this luscious Pumpkin Spice Buttercream that’s light, creamy, and perfectly flavored for the fall season—without the use of powdered sugar! It’s a delicious way to enhance your favorite desserts with the cozy, spiced flavors of pumpkin.