Brown the butter by melting it in a saucepan over medium heat until it becomes shimmering and brown, about 5–7 minutes.

Cool the butter mixture for 15–20 minutes in a mixing bowl.

Mix dry ingredients: gluten-free flour, baking soda, and kosher salt in a separate bowl.

Combine light brown sugar and granulated sugar into the cooled butter mixture.

Add egg, milk, and vanilla extract to the mixture, stirring until smooth.

Fold in the dry ingredients carefully until just combined.

Gently add in the English toffee bits into the dough.

Chill the dough for at least 2 hours.

Preheat oven to 350°F (175°C) and prepare baking sheets.

Scoop dough into balls onto prepared baking sheets.

Bake for 11–12 minutes until edges are golden and centers are soft.

Shape cookies while warm with a cookie cutter.

Cool on the baking sheets for about 10 minutes before transferring to wire racks.