Preheat your oven to 350°F and lightly grease your baking sheet. While the oven heats, sift together the flour, baking powder, and salt in a medium bowl—sifting removes lumps and helps the dry ingredients distribute evenly throughout the dough. Set this dry mixture aside. This prep work ensures everything is ready when you need it, so the mixing process stays smooth and efficient.

In a large mixing bowl, beat together the room-temperature butter, oil, and sour cream for about 1 minute until they're well combined and creamy. The butter and oil create a tender crumb, while the sour cream adds richness and moisture to keep these mini cookies soft. I always use full-fat sour cream because it gives the cookies a noticeably better texture compared to low-fat versions.

Add the sugar and vanilla to the wet mixture from Step 2, then beat on medium speed until the mixture is smooth and well combined, about 1-2 minutes. Gently fold in the dry ingredient mixture from Step 1 using a spatula or wooden spoon, stirring just until a soft dough forms—don't overmix, as this can lead to tough cookies. The dough should come together easily but still be slightly sticky.

Roll the dough into 3/4-inch balls and place them about 2 inches apart on your prepared baking sheet. Using the bottom of a glass (lightly dipped in water if it sticks), gently flatten each ball to create uniform mini cookies about 1/4-inch thick. Even thickness ensures they bake evenly and all finish at the same time.

Bake the cookies for 8 minutes at 350°F—they should be set but still very soft when you remove them from the oven. Let them cool on the baking sheet for 5 minutes (they'll firm up slightly), then transfer them to a wire cooling rack to cool completely. Complete cooling is essential before frosting, otherwise the frosting will melt and slide off.

While the cookies cool, beat together the butter, milk, vanilla, and sifted powdered sugar in a medium bowl until smooth and creamy, about 2-3 minutes. The mixture should be spreadable but not too soft. I love using Kerrygold unsalted butter for frosting because it has a richer, slightly more complex flavor that really elevates the final result.

Divide the frosting from Step 6 into three bowls if you want multiple colors, or keep it in one bowl for a single color. Add red gel food coloring to create your desired shades—I recommend using concentrated gel coloring rather than liquid coloring because gel keeps the frosting at the right consistency without making it runny. Frost each cooled cookie generously, then immediately top with valentine sprinkles or coarse sugar while the frosting is still sticky so the decorations adhere properly.