Melt Butter: Melt the butter in a small saucepan over low heat.
Mix Sugar: In a medium bowl, combine the sugar with the melted butter.
Add Flavours and Eggs: Stir in the vanilla extract, then add the eggs, mixing until fully incorporated.
Incorporate Remaining Wet Ingredients: Add the pumpkin puree, milk, and sourdough discard. Mix until smooth.
Combine Dry Ingredients: In a separate bowl, whisk together the whole wheat flour, all-purpose flour, baking powder, baking soda, pumpkin spices, oats and salt.
Mix Dry and Wet: Gradually add the dry mixture to the wet ingredients, mixing gently until just combined.
Rest: Let the batter rest and hydrate for 15 minutes or overnight in the fridge for a long fermentation.
Preheat Oven: After rest, preheat your oven to 450°F (232°C).
Prepare Muffin Tins: Line muffin tins with muffin liners.
After Rest: Scoop the batter into each liner to the top until there's no batter left.
Bake: Place in the oven and immediately reduce the temperature to 350°F (175°C). Bake for 20-25 minutes, or until a toothpick comes out clean.
Cool: Let the muffins cool in the liners for a few minutes. If using silicone liners, allow them to cool completely before removing.
Enjoy: Enjoy your delicious sourdough pumpkin spice muffins!