Combine milk and lemon juice in a bowl and set aside to sour, about 5 minutes. Add beaten egg and melted butter; stir to combine.
Combine spelt flour, sugar, baking powder, baking soda, and salt in a large bowl. Stir gently into milk mixture until just combined; batter will be lumpy.
Heat a lightly oiled griddle over medium-high heat. Drop batter by large spoonfuls onto the griddle and cook until bubbles form and the edges are dry, 3 to 4 minutes. Flip and cook until browned on the other side, 1 to 2 minutes. Repeat with remaining batter.