Preheat the oven to 350 and spray your muffin tin or line it with muffin liners.

Cream the butter and honey in a food processor. Add the beets and eggs and puree until the beets are smooth.

Add the flour, rosemary, baking soda, and salt and mix until just combined.

Add walnuts, if using, and mix until well combined.

Spoon out batter into muffin tin and bake for 20 minutes.

Remove from oven and cool on rack.