COMBINE all ingredients in a bowl. Mash frozen blackberries into batter with a fork or sharp edge of a spatula (or leave whole).
SCRAPE batter into a mug - allow 3" of space above batter for expansion.
MICROWAVE 2:30-3:00 minutes.
Alternate Cooking Method Oven:
(Please note, oven cooking method is temporary guesstimate till fully tested!)
PREHEAT oven to 350°. Pour batter into a mug, bake for 25 minutes. I HIGHLY RECOMMEND making several at a time so you're not spending all that time for 1 muffin. :)
Notes
Note: These can be batch cooked too!*STEVIA NOTES: 1 scoop = the scoop that comes in stevia bottle = 1/32 of tsps = 1 packet stevia. If you do not have any of this, a few light shakes. If you do not like stevia, use more erythritol-based sweetener to compensate. It's not nearly as sweet so per scoop you may need to add 1-3 more tsp. to taste.