Combine the buttermilk (make sure to shake it first in case all the fat has gone to the top!), oats, and butter in a microwave-safe bowl. Microwave in 30 second increments, stirring briefly between each increment, until butter has melted. This usually takes 2-3 minutes for my microwave – longer if my butter is frozen. Once butter has melted completely into mixture (which should now be quite warm), let the mixture sit while you mix the dry ingredients together. The objective is to get the oats warm enough to soak up the buttermilk/butter.

While the oat mixture cools, measure out the dry ingredients mixture in a separate bowl and stir to combine.

By this point, the oat mixture should have cooled a bit and soaked up most of the milk/buttermilk. Now add the honey,  the vanilla, and the egg. Stir well to incorporate.

Fold the dry ingredients into the wet ingredients, stirring just enough to incorporate. (Folding the dry ingredients into the wet ingredients means less cleanup!)

Then gently fold in the berries. Parcel out the batter into 12 muffin tins. I use a large (3 tbsp) cookie scoop for this, but it’s not necessary. Just makes things a bit tidier. The tins can be quite full – the muffins only rise a little bit.

Check on them at 25 minutes. If you press on the tops, they should spring back. If you stick a toothpick / fork in them, no batter should come out. Let them sit for about 5 min before moving to a cooling rack so they don’t fall apart when you take them out. Err on the side of overbaking — there are so many berries in these muffins, they are unlikely to dry out in the oven.