Place Meyer lemons in a 2-quart saucepan with 4 cups water. Bring to a boil over high heat. Reduce heat and cover; simmer lemons until soft, about 25 minutes. Remove from heat and cool completely.
Preheat the oven to 350 degrees F (175 degrees C). Lightly grease two 9-inch cake pans, line the bottoms with parchment paper, and lightly grease the parchment paper.
Remove any stems from the lemons. Slice into quarters and remove all seeds.
Place the lemon quarters in the work bowl of a large food processor and process until fairly smooth, about 30 seconds. Add flour, sugar, butter, baking powder, and salt. Pulse about 10 times, just until the batter comes together into coarse crumbs with flecks of lemon rind. Pour in eggs and limoncello with the motor running; process until a thick, slightly grainy batter forms, 10 seconds or less.
Divide batter between the prepared pans.
Bake in the preheated oven until the tops are light gold and spring back lightly to the touch, and a toothpick inserted into the middle of each cake comes out clean, 20 to 23 minutes. Cool in the pans for about 5 minutes, then remove and finish cooling on baking racks.
Place 1 cake layer on a cake plate and cover with lemon curd. Top with the second layer and frost just the top, or top and sides, with cream cheese frosting.