Be careful not to overcook it. The microwave can be a sneaky culprit for drying out your cake if left in too long. I’ve burned more than one batch, so make sure you check it at the one-minute mark and then keep an eye on it from there.
Using frozen blueberries is great, but make sure to toss them in a bit of flour to prevent them from sinking to the bottom of the mug. I forgot this once, and I ended up with a layer of blueberries at the bottom that didn’t cook as nicely.
Finally, I recommend not skipping the lemon zest. It infuses such a fresh fragrance and flavor, and trust me, without it, the cake loses its special bright punch.
