Trim the beets and peel them as you would potatoes. Grate them in a food processor or by hand.

Toss the grated beets in a bowl with the rosemary and salt, then add about half the flour; toss well, add the rest of the flour, then toss again.

Put a medium-to-large ProCoat or CeramiClad™ Non Stick Frying Pan over medium heat, add 2 Tbsp. of the butter, and cook until it foams. Scrape the beet mixture into the pan and press it down with a spatula to reach the edges. Adjust the heat so that the pancake sizzles without burning and cook until the bottom of the beet cake is crisped and releases, 6—8 minutes. Slide the cake out onto a plate, add the remaining 1 Tbsp. butter to the pan, and set it back over the heat.

Top the pancake with another plate, invert the two plates, and slide the cake back into the pan. Continue to cook, adjusting the heat if necessary, until the second side is browned, another 6—8 minutes. Cut into wedges, sprinkle with more salt if you like, and serve.