In a mixing bowl, combine brown sugar and lemon zest, mixing until fragrant. Add in softened butter and cream together until fluffy. Follow by incorporating the egg and vanilla extract, blending thoroughly. Gradually mix in flour, baking powder, and salt until just combined. Chill the dough for 30 minutes to firm up, making it easier to scoop and shape into cookies.

In a saucepan, whisk together granulated sugar, fresh lemon juice, zest, egg yolks, and a pinch of salt. Cook the mixture over medium heat, stirring constantly until it thickens and reaches 170°F (76°C). Once thickened, strain the curd to remove lumps and immediately stir in cold butter until smooth. Transfer to a bowl and chill while preparing the cookies.

Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper. Scoop the chilled cookie dough onto the prepared sheet, spacing them about 2 inches apart. Bake in the preheated oven for 10-12 minutes, or until the edges are lightly golden. Once baked, allow the cookies to cool completely on a wire rack.

In a heatproof bowl, combine egg whites and granulated sugar. Place the bowl over simmering water, whisking gently until the mixture reaches 170°F (76°C) and the sugar dissolves. Remove from heat and use an electric mixer to whip the egg whites until they form stiff peaks and appear glossy.

Take each cooled cookie and generously top with a spoonful of the chilled lemon curd. Then, using a spatula or piping bag, swirl the fluffy meringue on top of the lemon curd, creating pleasing peaks.

If you desire a beautifully toasted meringue, carefully use a culinary torch to lightly toast the meringue peaks until golden brown. Keep the torch moving evenly to avoid burning any sections.

Once the meringue is toasted, your delicious Lemon Meringue Pie Cookies are ready to be served! These cookies are best enjoyed fresh the same day, but they can be stored in an airtight container in the refrigerator for a couple of days.