1. Prepare candied lemon slices by boiling water and sugar until sugar dissolves. Add lemon slices, simmer gently for 10 to 15 minutes, then cool.
2. In a medium bowl, whisk together flour, baking powder, baking soda if using, sugar, salt, and poppy seeds.
3. In a separate bowl, combine ricotta, milk, egg yolks, vanilla, lemon zest, and lemon juice. Mix well.
4. Gradually add the dry ingredients to the wet ingredients and whisk until just combined, keeping some lumps for fluffiness.
5. Beat egg whites separately until stiff peaks form, then gently fold into the batter to create a light and airy texture.
6. Heat a greased griddle or nonstick skillet over medium to medium-high heat. Pour batter with a ¼ to ⅓ cup scoop per pancake. Cook about 3 to 4 minutes on one side until bubbles form and edges look set, then flip and cook another 2 to 4 minutes until golden brown. Adjust heat as needed to avoid burning.
7. Serve warm topped with butter, candied lemon slices, lemon syrup, maple syrup, powdered sugar, or blueberry sauce if desired.