Preheat the oven to 350 degrees F. Coat a 12 x 17 inch, rimmed baking sheet with nonstick spray and line the bottom with parchment. Set aside.
Whisk together the flour, soda salt, and spices in a bowl and set aside.
In a large bowl beat the butter and sugars together until creamy and pale, about 3 minutes. Add eggs and yolk one at a time, scraping down as needed. Add vanilla and molasses and mix until combined. Add flour mixture on low speed until combined.
By hand, stir in white chocolate and chopped ginger.
Spread batter evenly into prepared baking sheet and bake until golden on edges, 22 to 25 minutes. Let cool completely in the pan; cut into squares.
Blondies can be stored in an airtight container at room temperature for up to 1 week.
Notes
Look for crystallized ginger in the bulk bins at the grocery store instead of in a little jar in the spice section - it’s generally less expensive in bulk.
This recipe calls for unsulfured molasses because it isn’t as bitter as blackstrap molasses.
Don’t add all of the white chocolate to the batter - instead save about ½ cup and sprinkle it on the top of the batter and lightly press them in before baking the bars.
These bars store well in the freezer for up to three months - be sure to put a piece of parchment between the layers of cut and cooled gingerbread blondie bars.