Preheat oven to 350ºF/180ºC/gas 4. Generously spray two 12-cup muffin pans with cooking spray. Sprinkle the bottom of each cavity with a couple pinches of sugar. Set aside.
Add almonds and rosemary to your KitchenAid® K400 Blender. Close lid, select “Ice Crush” setting, and let blender run through the setting. Scrape down the sides of the blender with a rubber spatula, then replace lid and blend on speed 5 for 10 seconds. Scrape sides again and blend on speed 5 for a final 15-20 seconds, or until almonds and rosemary are finely ground.
Pour the almond mixture from blender in a small mixing bowl. Add all-purpose flour, baking powder, baking soda, and salt. Whisk to combine, and set aside.
Place ricotta cheese, olive oil, orange zest and sugar into the blender. Pulse 5 times to incorporate. Remove the lid cap and add eggs, one at a time, pulsing once after each addition. Replace lid cap.
Remove lid, use spatula to scrape down the sides of the bender, then add half of flour mixture to blender and pulse 2 times. Scrape down sides of blender again, then add remaining flour mixture and blend on speed 3 for 15 seconds.
Assemble the cakes. Use a sharp knife to cut off the ends of four of the citrus fruits. Slice the citrus into very thin rounds, no thicker than 1/8". Remove any seeds from the rounds and place one small citrus round in the bottom of each sugared muffin cavity. (See Chef’s Notes for choosing/placing citrus.)
Slowly fill each muffin cavity to a little more than halfway full. (A pastry spatula is helpful in portioning the batter from the blender and into the cavities.) Bake cakes for 20-25 minutes, rotating the pans halfway through baking. Cakes are done when a toothpick inserted into the cakes comes out clean.
