Muffins:

• 150g all-purpose flour
• ¾ tsp baking powder
• 1/4 teaspoon baking soda
• 1.5 tsp ground cinnamon
• 1/4 tsp ground nutmeg
• 1/8 tsp pumpkin spice
• 1/4 tsp salt
• 43g butter melted
• 85g brown sugar
• 75g granulated sugar
• 1/2 tsp vanilla extract
• 3 tbsp milk
• 1 egg
• 175g sourdough starter – active and bubbly 

Icing: 

• 145g powdered sugar

• 15g melted butter 

• 1 tsp vanilla

• 2 tbsp milk