1-First Step: Prep Your Workspace Preheat oven to 350°F. Grease and flour two 8-inch round pans or line with parchment. Gather all ingredients at room temperature for smooth mixing. This mise en place prevents lumps and ensures even baking. For dietary tweaks, have substitutes ready now.

2-Second Step: Mix Dry Ingredients In a bowl, whisk 2 ½ cups all-purpose flour, 2 tsp baking powder, and ½ tsp salt. Set aside. This step aerates the flour for tenderness. Gluten-free? Use your blend here.

3-Third Step: Cream Butter and Sugar Beat 1 cup softened unsalted butter and 1 ¾ cups granulated sugar on medium until pale and fluffy, about 3 minutes. Scrape the bowl often. This incorporates air for a light cake from scratch.

4-Fourth Step: Add Eggs and Vanilla Add 4 large eggs one at a time, beating well after each. Mix in 2 tsp vanilla extract. Batter may look curdled; it smooths later. Vegan adaptation: Use flax eggs, blending thoroughly.

5-Fifth Step: Combine Wet and Dry Alternate adding dry mix and 1 ¼ cups whole milk, starting and ending with dry. Mix on low just until combined, about 1 minute. Overmixing toughens the crumb.

6-Sixth Step: Fold in Sprinkles Gently fold in ½ cup rainbow jimmies with a spatula. Stir last to keep colors vibrant and prevent sinking. Low-calorie tip: Use fewer sprinkles on top.

7-Seventh Step: Bake the Layers Divide batter evenly between pans. Bake 25-30 minutes until toothpick comes out clean and edges pull from sides. Rotate halfway for even browning. Cool in pans 10 minutes, then on racks fully.

8-Eighth Step: Make Vanilla Buttercream Beat 1 cup butter until creamy. Gradually add 4 cups powdered sugar, 2 tsp vanilla, and 3-4 tbsp milk. Whip until fluffy. Adjust milk for spreadable texture.

9-Final Step: Assemble and Serve Level cooled layers if needed. Frost between, top, and sides. Add extra sprinkles for flair. Slice and enjoy! Store as below. This scratch funfetti layer cake wows at parties.