Drop the pecan pieces into the bottoms of four muffin cups.

Pour the custard mixture over the pecans, gently urging it down around the nuts (but don't stir). Fill the cups to the brim. Slide that into a 275F degree oven and cook for about 40 minutes.
  
 
 Step 8:

When it's ready, the custard will be just separating (on its own) from the sides.
 
 Step 9:

Remove from the oven and let cool until warm. Remove from the cups, invert (so the nuts are on top) and cool in the refrigerator.
  
 
 Step 10:

Put the chocolate and 1 tbsp butter into a microwave-safe bowl or cup and microwave for a couple of minutes, until the butter melts and you can swirl it into a smooth chocolate sauce. Pour over the acorn squash custards and return them to the fridge.