In a large microwave-safe bowl, melt the butter. Let it cool to room temperature. Make sure it’s not hot to avoid greasy cookies.

Once the butter has cooled, add the granulated and brown sugars. Whisk well. Add the egg and egg yolk, whisking until emulsified and creamy.

Add the remaining cookie ingredients and mix until there are no dry streaks. If needed, switch to electric hand mixers. Don’t overmix. Cover the dough tightly and refrigerate for 1 hour.

Line a sheet pan with parchment paper. In a medium bowl, add all the filling ingredients and whisk until smooth.

Transfer the filling to a piping bag or zip-top bag. Pipe about 1 teaspoon-sized dollops onto the prepared sheet pan. You should get around 25 dollops. Freeze until firm. If filling won't squeeze out of piping bag you may need to pop in the microwave and rewarm for 10 seconds.

Preheat the oven to 350°F.

Place ½ cup granulated sugar in a bowl. Measure out cookie dough balls (2 packed tablespoons or 40 grams each). Press a frozen filling puck into each dough ball and roll the dough around it, ensuring it's fully enclosed. Roll each ball in granulated sugar.

Arrange 8 cookie balls on a silicone-lined baking sheet. Refrigerate for 15-20 minutes until firm. Bake for 10-12 minutes, being careful not to overbake. Slightly underbaked is best.

If any cookies have uneven edges after baking, immediately press them inward with a metal spatula. Let the cookies rest on the sheet for 5 minutes, then transfer to a cooling rack. Allow them to fully cool before glazing.

In a large bowl, whisk together all the glaze ingredients until smooth. If too thin, add more powdered sugar until thick.

Spoon the glaze over the cooled cookies. Use a toothpick to pop any air bubbles. Let the glaze set for about 20 minutes before serving.