Preheat oven to 400°F. Grease and lightly flour a muffin pan, or use cupcake liners. To make buttermilk, measure out the milk and whisk in lemon juice or white vinegar. Set aside for at least 5 minutes.
In a large bowl, whisk together the wet ingredients including the buttermilk. In a separate bowl, whisk together the dry ingredients.
Add dry to wet and mix until just combined with no streaks of flour remaining.
Divide the muffin batter evenly among the prepared muffin pan, filling all 12 cavities. All batter should be used. Bake in preheated oven for 18–23 minutes or until a toothpick inserted in the center comes out clean or with moist crumbs.
Allow to slightly cool, about 5 minutes, before gently removing them to a cooling rack.
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Notes
Note 1: Use a good nonstick muffin tin for easy muffin removal. These pumpkin chocolate chip muffins always come out perfectly from this pan!Note 2: Be sure to use pure canned pumpkin not pumpkin pie filling. Note we’re only using 1 cup pumpkin, not the entire can!Storage: Cool the muffins completely, then store in an airtight container, unrefrigerated, for up to 2 days. You can also refrigerate in an airtight container for up to a week, or wrap individually, seal in a freezer bag; freeze for up to 3 weeks.