Prep the pan and oven: Line a 12-cup muffin pan with liners. Preheat oven to 350°F (175°C).
Mix dry ingredients: In a large bowl, whisk flour, sugar, baking powder, baking soda, and salt until combined.
Mix wet ingredients: In another bowl, whisk eggs, milk, oil, sour cream, and vanilla until smooth.
Combine batter: Pour wet ingredients into dry.
Stir gently with a spatula until just combined. Do not overmix; a few small lumps are fine.
Fill liners: Divide batter evenly among liners, about 2/3 full each.
Bake: Bake 16–19 minutes, until the tops spring back or a toothpick comes out clean. Cool in pan 5 minutes, then transfer to a rack to cool completely.
Make buttercream: Beat the softened butter on medium-high until creamy, about 2 minutes.
Add powdered sugar 1 cup at a time, beating on low until incorporated. Add vanilla, salt, and 2 tablespoons cream. Beat on medium-high until fluffy, 2–3 minutes.
Adjust with more sugar for thickness or more cream for softness.
Tint frosting: Divide buttercream into bowls. Leave some white. Tint portions gray (small dab of black gel), black, pink (for ears and noses), and any other cat colors you like.
Use gel color for vibrant shades without thinning the frosting.
Base frosting layer: Pipe or spread a smooth mound of frosting on each cupcake using a round tip or a spoon. This is your “face.”
Add ears: Pipe two small triangles of pink and gray frosting at the top edge for ears. Or press in white chocolate chips point-side up and add a tiny pink dot inside each for inner ears.
Eyes and nose: Press in mini chocolate chips for eyes.
Add a pink heart sprinkle or a small pink candy for the nose, centered below the eyes.
Whiskers and mouth: Add 3 short pieces of licorice lace or sprinkles on each side for whiskers. Draw a simple “3” shape or a small smile with melted chocolate in a piping bag or an edible marker.
Details and variations: For tabby stripes, pipe thin lines of darker frosting on the forehead. For tuxedo cats, use white frosting for the lower half of the face.
Keep designs simple and playful.
Set and serve: Chill the decorated cupcakes 10–15 minutes to set the details. Serve at room temperature for the best texture.