To make the sugar cookies:

• Make the cookie dough. Add the sifted flour, cornstarch, baking powder and kosher salt to a large bowl and whisk to combine; set aside.
• Using a stand mixer fitted with the paddle attachment or an electric hand mixer, cream the butter and sugar on medium-high speed until light and fluffy, about 5 minutes, scraping down the sides and bottom of the bowl halfway through and again at the end. Mix in the egg and both extracts.
• Add the dry ingredients to the batter in 2 additions, mixing on low speed until just combined after each addition. Be careful not to overmix the dough.
• Turn the cookie dough out onto a large piece of plastic wrap. Press the dough into a large disc, about 1/2″ thick, then wrap the dough tightly in the plastic wrap (TIP: lightly flour your hands if the dough is sticky).
• Chill the dough. Place the dough in the fridge to chill for 2 to 3 hours. Towards the end of the chill time, preheat the oven to 350°F and line 2 large baking sheets with parchment paper.
• Roll and cut out the dough. Place the chilled dough on a clean, floured work surface. Lightly flour the top of the dough and your rolling pin. Roll the dough into an even 1/4″ thickness, re-flouring the surface and/or dough as needed to prevent sticking. Use a cookie cutter to cut the dough into heart shapes, gathering and re-rolling the scraps until you’ve used up all of the dough (TIP: if the dough begins to get too sticky, press it into a disc, wrap it in plastic wrap and place in the freezer for 5 minutes to firm up).
• Place the heart-shaped cutouts on the prepared baking sheets, spacing 1 to 2-inches apart. Place in the fridge to chill for 10 minutes (TIP: if your baking sheets don’t fit in the fridge, place the cutouts on large plates).
• Bake. Bake for 8 to 10 minutes, until the edges are set and the tops of the cookies are no longer shiny. Rotate the pan as needed if your oven tends to be warmer in the back. Allow the cookies to cool on the baking sheet for 5 minutes before removing to a wire rack to cool completely.

To make the icing/ Decoration:

• Make the icing. Add the sifted powdered sugar, egg white, 3 tablespoons milk and almond extract to a large bowl and whisk to combine; it will be very thick at first, but keep stirring! Add more milk if necessary, 1 tablespoon at a time, until the glaze is still thick but flows off your whisk like honey. Stir in a few drops of gel food coloring.
• Decorate. Line a large baking sheet with parchment paper; set aside. Dip the top side of each cookie into the icing, holding the cookie over the bowl to let excess drip off. Use a toothpick to pop any bubbles that appear. Place the iced cookie on the prepared baking sheet and top with sprinkles. Repeat this process with each cookie.
• Set. Allow the icing to dry, about 30 minutes to 1 hour.