Prep: Preheat oven to 350°F (175°C). Grease cake pan(s) and line with parchment paper.
Dry Mix: Whisk flour, baking powder, and salt in a bowl. Set aside.
Cream Butter & Sugar: Beat butter, granulated sugar, and brown sugar until fluffy (3–4 mins).
Add Eggs & Vanilla: Mix in eggs (one at a time) and vanilla extract.
Alternate Dry/Wet Ingredients: Add 1/3 flour mix, then ½ milk, repeating until combined. Avoid overmixing.
Bake: Pour batter into pan(s). Bake 30–35 mins (toothpick should come out clean).
Cool: Let cool in pan for 10 mins, then transfer to a rack.