In a large bowl, toss together the Brussels sprouts, oil, rosemary, salt and pepper.
Arrange the Brussels sprouts in a single layer cut side down on a large non-stick baking sheet, making sure there is space between them.
Place pieces of the torn prosciutto around the Brussels sprouts.
Roast for 16-18 minutes, or until the Brussels sprouts are fork tender and the prosciutto is crispy. (Check occasionally to make sure the prosciutto isn’t browning too much).
Remove from oven and toss with maple syrup. Roast for another 2-3 minutes and serve immediately.
Notes
To ensure even cooking, Brussels sprouts should be roughly the same size. If you have some larger ones, you may want to quarter them.
The prosciutto may stick to the pan a little, so be sure to use a non-stick pan or line your baking sheet with parchment paper. (Note that if you use parchment paper, your Brussels sprouts may not brown as much).
If your Brussels sprouts are taking longer than expected to cook, you might want to remove the prosciutto so it doesn’t burn.