Preheat oven to 350° F / 176° C. Line an 8 x 8-inch square baking tin with parchment, allowing a 1-inch overhang on all sides.

In a medium bowl, whisk together all-purpose flour, ground cardamom, baking powder, and kosher salt.

In a separate bowl or the bowl of a stand mixer, whip butter on high speed until soft and fluffy. Mix in the light brown sugar, followed by the egg, whole milk, molasses, and vanilla bean paste.

With a rubber spatula, fold in the dry ingredients until just combined.

Fold in the ruby chocolate, reserving a few callets for decoration.

With a rubber spatula, spread batter evenly into prepared tin.

Press reserved ruby chocolate callets on top.

Bake in preheated oven for 35-40 minutes, or until golden brown and a toothpick comes out mostly clean, and the center no longer jiggles.

Allow blondies to cool completely in the tin. Slice into squares and serve.

Store leftover ruby chocolate blondies in an airtight container at room temperature for up to three days.