1-First, whisk together the all-purpose flour, cake flour, baking powder, instant coffee, and salt in a bowl to combine the dry ingredients evenly.

2-Next, beat the butter and sugar on medium-high speed until they turn light and fluffy, which helps create that perfect cookie base.

3-Then, add the egg yolks and beat until everything mixes well, making sure to scrape the sides of the bowl as you go.

4-Gradually add the flour mixture, alternating with the Irish cream liqueur, until it forms a dough ball that holds together nicely.

5-Roll out the dough on a floured surface and cut it into rounds with a cookie cutter, placing them about 1 inch apart on a parchment-lined baking sheet.

6-Bake at 350°F (175°C) for 15-18 minutes, then transfer the cookies to a wire rack to cool completely.

7-For the Irish cream filling, start by beating the egg yolks until they look light in color, setting up a smooth base.

8-In a small pan, combine the lemon juice, sugar, and corn syrup, stirring until the sugar gets moist, then heat it over medium-high until it boils and the sugar dissolves.

9-Remove from heat and slowly beat this hot syrup into the egg yolks in a thin stream, continuing to beat until it thickens, and let it cool completely.

10-Once cooled, add the butter, Irish cream liqueur, and powdered sugar to a stand mixer bowl and beat until smooth and shiny.

11-To assemble, spread the filling on the flat side of half the cookies using a spatula, then top with the remaining cookies, flat sides down.

12-Using tips like a lightly floured surface and cookie cutter helps prevent sticking, while baking until firm keeps the shape just right.