Step 1

Heat oven to 350°F. Butter 8-inch square baking dish and line bottom with parchment paper, leaving overhang on each side. Butter paper.

Step 2

Melt chocolate and 1/2 cup butter in medium saucepan on low, stirring occasionally, until smooth. Remove from heat, let cool slightly, then whisk in sugar, beets, vanilla, espresso powder and salt. Whisk in eggs one at a time until fully incorporated. Fold in flour until just combined.

Step 3

Pour batter into prepared baking dish and bake until knife inserted in center comes out clean or with just a few moist crumbs attached, 30 to 35 minutes. Let cool in pan 10 minutes, then use overhangs to transfer to cutting board. Cut into 16 squares.