Preheat oven to 350F; parchment-line 8x8 pan.

Whisk flour, cocoa, and sugar; stir in coconut oil, plant milk, and vanilla.

Gently fold in most blueberries, keeping whole.

Spread batter in pan; dot remaining blueberries on top.

Bake 30 to 32 minutes until center sets.

Cool fully; chill briefly before cutting squares.