Preheat oven to 350°. Spray a 9-inch square baking pan with baking spray with flour. Line pan with parchment paper, letting excess extend over sides.
In a large bowl, whisk together flour, baking powder, and salt. Whisk in melted butter and vanilla extract. (Mixture will be thick.)
In the bowl of a stand mixer fitted with the whisk attachment, beat together sugar and eggs at high speed until tripled in size, 4 to 5 minutes. Add one-third of egg mixture to flour mixture, stirring just until combined. Fold in remaining egg mixture in 2 portions until well combined. Fold in chocolate chips. Pour batter into prepared pan. Drop cherry preserves by teaspoonfuls onto batter. Using the tip of a chop-stick or knife, swirl preserves into batter.
Bake until a wooden pick inserted in center comes out clean, 20 to 30 minutes, covering with foil after 10 minutes of baking to prevent excessive browning. Let cool completely on a wire rack.
Using excess parchment as handles, remove from pan, and cut into 36 (1½-inch) squares. Store in an airtight container at room temperature for up to 4 days.
Recipe by TeaTime Magazine at https://teatimemagazine.com/blondie-bites-with-cherry-preserves/