For the salad: Preheat the oven to 375 degrees F. Line a baking sheet with parchment.
Cut the broccoli heads into florets and then chop in bite-size pieces. Place in a large salad bowl.
When the oven is preheated, place the prosciutto on the prepared baking sheet. Cut biscuit dough scraps into bite-size pieces and place them on a separate baking sheet. Bake the biscuit scraps for 10 minutes and the prosciutto for 15, turning the baking sheets after 7 minutes. Allow to cool, then break the prosciutto into small pieces.
Add the onions and prosciutto pieces to the salad bowl and toss gently to distribute.
For the dressing: In a small mixing bowl, add the balsamic vinegar, maple syrup, mustard, chili paste, salt, pepper and garlic; whisk to combine. Whisk in the olive oil in a slow, steady stream until the dressing emulsifies and thickens.
Pour a little less than half of the dressing over the broccoli mixture, or add to taste; toss to coat evenly. Top with biscuit croutons just before serving.
Save the extra dressing in a jar, refrigerated, for future salads.