In a bowl, whisk together the flour, salt, and baking powder; set aside.

In a large stand mixer, combine the butter and sugar, and mix until fluffy and well-mixed, about 1-2 minutes.

Add the eggs one at a time, beating well after each addition; then add the vanilla extract and sour cream.

With the mixer on low, gradually add the dry ingredients, mixing until just about incorporated. Stop when only a few streaks of flour remain, scrape the bowl, and mix by hand until fully combined.

Divide the dough in half, press into discs, wrap in plastic wrap, and refrigerate for about 30 minutes.

Preheat oven to 350°F. Roll out each disc between sheets of parchment to 1/4-inch thick.

Cut out cookies using a heart-shaped cookie cutter and place on a parchment-lined baking sheet.

(Optional) Freeze cut-out cookies for 10 minutes before baking.

Bake for 10-12 minutes until edges are starting to color, then cool on a wire rack.

To make royal icing, mix meringue powder and water until foamy, then add sifted powdered sugar and mix on low until incorporated.

Add corn syrup and almond extract, then mix on medium-high for 5 minutes until shiny and stiff.

Divide the icing; keep half white and color the remainder as desired.

If needed, thin colored icing with water until it takes about 15 seconds for the trail to disappear.

Place icing in piping bags and decorate cookies by flooding with white icing and adding designs as desired.