I don’t know why every recipe I’ve ever read instructs to microwave chocolate on HIGH power. I thought it was some complicated reason I couldn’t understand. A year ago, I tried microwaving chocolate on LOW just for kicks. I’ve never gone back to HIGH power since.
Microwaving on LOW power is much more forgiving — especially if you are a home cook melting a low volume of chocolate for a single recipe, or even just for garnish. On HIGH, five seconds can be the difference between solid chocolate and burning your chocolate. Yes, LOW takes longer, but if you’ve ever tediously chopped a block of (expensive) Callebaut, you’ll probably be okay waiting the extra minute or two.
This applies to heating milk, too. I used to always overheat milk. Recently, I made a chocolate-coconut cake and I wanted a chocolate ganache-type glaze, but not as hard as a ganache. I didn’t want the chocolate to be too dark, either. All I had was a block of 60% Callebaut I had purchased from Whole Foods, butter, and whole milk. I chopped up about 3.5 oz of the chocolate, threw it on top of 6 tbsp of butter cut into pieces, and set that aside. Then I added 2-3 TBSP sugar to 1/2 cup of milk in a Pyrex measuring cup, and microwaved it on LOW for a minute. To my surprise, my large-crystal sugar1 had dissolved quite nicely; I didn’t even need to stir (correction: I may have needed to stir). I set that aside, and microwaved the chocolate on LOW, checking every 30 seconds. I took it out when it looked right and whisked it to combine the butter and chocolate. (A small whisk like this one is what I prefer for this purpose.) There was one stubborn piece of chocolate that wouldn’t cooperate, so in it went again for 15 seconds on LOW. I whisked until it was completely smooth. Then, I slowly added in the still warm milk, adding a little at a time and whisking as I poured it. I tasted as I went along so I could stop if it was sweet enough; I’d rather have it be too thick than too sweet. I went a little past the consistency I wanted because the glaze thickens as it cools. (There was unused milk left over.) I let the glaze cool slightly and then poured it over the cake. The cake wasn’t perfectly level, so I poured over some tricky edges at the end, after the glaze had cooled/thickened some more.
I’m not a chocolate expert by any means, but microwaving chocolate on LOW has saved me a lot of trouble.
1 Likely this was because my sugar contains more moisture than regular sugar. I purchase Zulka Morena sugar from Weis Market (corner of Security Blvd and Rolling Rd) to try to avoid bone char and refinement. It tastes better, too.