Preheat oven to 350F. Line a baking sheet with parchment paper.

Spread out pretzels in a single layer on lined baking sheet. Evenly pour butter over pretzels and sprinkle sugar on top.

Bake pretzels until the butter and sugar have caramelized, about 8 - 10 minutes.

Remove from oven and allow pretzel brittle to cool completely. Break brittle into large pieces, about 3 - 5 (or more!) pretzels per piece. You want to have a minimum of 14 brittle pieces for the 14 cookies.

Line a large baking sheet with parchment paper. Set aside.

In the bowl of a stand mixer fitted with a paddle attachment, cream the butter, brown sugar, and granulated sugar on medium speed until they are smooth, about 1 minute.

Add the vanilla and egg to the butter mixture and mix on medium speed until they are fully incorporated, scraping down the sides of the bowl as needed.

In a food processor, grind pretzels into a fine flour, some coarser pieces are okay. This is your pretzel flour.

In a medium bowl, whisk together the flour, pretzel flour, salt, baking powder, and baking soda. With the mixer on low speed, add the flour mixture in two batches to the butter mixture, and mix until the ingredients are just combined, about 1 minute.

Add white chocolate pieces to the bowl, and mix until they are just incorporated with the dough, about 30 seconds.

Dollop strawberry jam into the dough and gently fold the jam to form ribbons in the dough.

With a standard ice cream scoop, form 14 even balls of dough.

Place filled dough balls about 2 inches apart on the baking sheet. If there are big puddles of jam on the edges of the dough balls, use a spoon or spatula to push the jam upwards onto the dough ball. Jam that is close to the pan will burn much quickly than the time it takes the cookie to cook.

Bake the cookies for 12 to 14 minutes, or until the cookies are browned and caramelized along the edges and the centres are just set. If you would like your cookies to have the crinkled edges, give the pan a few taps on the oven rack before you take them out of the oven.

Upon taking the cookies out of the oven, gently press a piece of pretzel onto each cookie. Pushing the brittle onto exposed white chocolate will help the brittle adhere to the cookie.

Allow the cookies to cool on the baking sheet for 10 minutes, then transfer them to a wire rack to cool completely.