Start by preheating your oven to 400°F. While it heats, gather all ingredients and ensure your butter and egg are at room temperature—this helps them incorporate smoothly into the dough for a better texture. Finely grate your lemon zest (I find a microplane works best for getting the bright flavor without the bitter white pith) and squeeze your lemon juice fresh if possible, as it makes a noticeable difference in the final taste.

In a medium bowl, whisk together the flour, baking powder, and salt. This combines your leavening agent evenly throughout and prevents dense pockets in your cookies. Set this mixture aside for now.

In a large bowl, beat together the softened butter, sugar, and lemon zest for about 3 minutes until the mixture is light, fluffy, and pale. This creaming step is crucial—it incorporates air into the dough, which helps the cookies spread slightly and bake evenly. The lemon zest added here infuses the dough with bright citrus flavor from the start.

Beat the room-temperature egg into the butter mixture, then add the lemon juice and vanilla extract. Mix until fully incorporated and the dough looks smooth and slightly glossy. Using room-temperature eggs prevents the mixture from seizing and ensures everything blends seamlessly.

Add the dry ingredient mixture from Step 2 to the creamed wet ingredients and fold together until just combined. Don't overmix—you want a cohesive dough that comes together without any visible flour streaks. Overworking the dough can make the cookies tough, so stop mixing as soon as everything is incorporated.

Transfer the dough to a piping bag fitted with a star or fluted tip (this creates those classic spritz cookie shapes). Pipe small, uniform cookies directly onto an ungreased baking sheet, spacing them about an inch apart. Immediately sprinkle pink and yellow sanding sugar over each cookie while the dough is still sticky—this helps the sugar adhere and creates a beautiful, sparkly finish.

Bake in your preheated 400°F oven for 6-8 minutes, until the edges are just barely golden brown but the centers still look slightly underbaked. The cookies will continue to set as they cool. Let them rest on the baking sheet for 5 minutes (this allows them to firm up enough to move without breaking), then transfer to a wire cooling rack to cool completely. I like to bake a test batch first to see how your oven runs—every oven is slightly different, and you want these cookies tender and delicate, not crispy.