Cook beets. For oven roasting wrap beets in foil and roast at 450° for 1 hour. To pressure cook add 1 cup of water to the cooker. Place beets on the steamer rack and cook on high 13 minutes. Quick release. (or according to your pressure cooker instructions).
Allow beets to cool until you are able to handle and peel. Coarsely grate beets until you have 3/4 cup. Reserve any remainder for another use.
Put grated beets in a large bowl and add the ricotta, egg, 3/4 cup Parmesan cheese, salt, pepper and 1 cup of the flour. Stir well to mix thoroughly. (You can make this 'dough' a day ahead and refrigerate.)
Dust a platter or baking sheet with flour. Put the remaining 1/2 cup of flour in a small bowl.
Divide the dough into 6 equal portions. Roll the dough into a rope about 1 1/2" in diameter. Cut off 1 1/2" sections. Pinch the 2 ends of each section and bend toward the center to form a crescent shape. Optional: gently score the top with a fork. This makes more surface to hold sauce and seasonings. Transfer gnocchi to the prepared floured sheet. Repeat until all the dough has been shaped. You can refrigerate gnocchi, covered for up to 6 hours if you like at this point.
While water is coming to a simmer, melt butter in a large saucepan with rosemary sprigs. Set aside if it is ready before the gnocchi is cooked.
Bring a large pot of salted water to a simmer. You may need to work in batches at this point to not overcrowd the gnocchi. Gently drop the gnocchi into the water and cook until they come to the surface and float. Cook another 2 minutes. While gnocchi is cooking return the butter to the heat. Use a slotted spoon to drain and transfer the cooked gnocchi to the skillet. Stir gently till all the gnocchi is coated.
Transfer to a serving plate and sprinkle generously with 1/2 cup remaining of grated Parmesan cheese.