Preheat your oven to 375 degrees F. Line a baking sheet with parchment paper. Set aside.
In the bowl of an electric mixer, fitted with the paddle attachment, combine the butter, Biscoff butter, brown sugar, granulated sugar, and vanilla. Beat on medium speed until well blended, about one minute.
Add the eggs and beat until just combined.
Add the flour, baking soda, and salt and mix on low speed until just combined.
Stir in the white chocolate chips and cookie chunks.
Using a large cookie scoop, (mine made 3.5 ounce cookies), scoop the cookie dough into 20 cookies. Break each cookie in half, imprint each half with your thumb and fill one side with 2 teaspoons of Biscoff butter. Put the two cookie dough halves together and shape into a ball. Repeat for all the cookies.
Bake for 11 to 12 minutes, or until slightly golden brown on top. Do not over bake. In fact, I like these underdone just a little. Let the cookies cool for about 10 minutes before eating.
Makes about 20 large cookies.