Preheat oven to 400°
In a large bowl, mix together the sourdough discard, sugar, melted butter, milk, egg, lemon zest, and vanilla extract until everything is fully combined.
Then fold in the flour, baking powder, baking soda, salt, and poppy seeds. Be sure to fold in the batter, not overmixinng.
Scoop into muffin tins that are lined or greased. Optional to sprinkle raw sugar onto the tops before they bake.
Bake for 13-15 minutes.