In a small mixing bowl combine the flour, baking powder, and salt. Stir to combine, set aside.
In a medium mixing bowl combine the melted butter and sugar, whisk to combine. Add in the egg and vanilla. Slowly mix in the milk. Add in the dry ingredients and mix until combined and lump free. Add in the lemon juice, zest, and poppy seeds, stir to combine.
Heat a large skillet or griddle over medium heat, grease with butter or cooking spray. Use a 1/3 cup dry measuring cup, pour batter onto the greased griddle, cook over medium until bubble start to form on top of the pancake 2-3 minutes. Flip and cook for a another 1-2 minutes until set. Transfer to a plate and repeat with the remaining batter. Serve with soft butter, maple syrup, extra poppy seeds, and fresh lemon wedges.