In a medium bowl, whisk together the yogurt and milk until smooth. Stir in the oats. Set aside to soak for 10-15 minutes.
Stir in the rest of the wet ingredients into the oat mixture.
In a large mixing bowl, combine all the dry ingredients. Add the wet ingredients. Be careful not to over mix. Use a spatula (instead of a whisk) to gently stir together until all the flour is wet. The less you stir the mixture, the lighter and fluffier your muffins will be.
Gently fold in the blackberries.
Divide batter evenly into a greased, lined or silicone 12-cup muffin pan.Bake for 18-20 minutes, or until a toothpick inserted into the center of a muffin comes out clean.
Allow the muffins to cool for 3-5 minutes before transferring to a wire rack to cool completely.
Notes
Take all the cold ingredients out of the refrigerator at least 15 minutes prior to cooking.
If your blackberries aren't very sweet, you can add up to ⅓ cup honey
You can also substitute honey with: one medium overripe banana (will be about ½ cup mashed) or ½ cup unsweetened applesauce.
Do NOT leave out the lemon zest!
Store in an airtight container at room temperature for up to 2 days. Refrigerate for up to 4 days. Enjoy at room temperature or microwave briefly. Freeze for up to 3 months.