NB: I usually decrease the amount of olive oil to 1/3 cup and use the full 6 tablespoons of balsamic

Assembling the salad:

Soak onions in 1/2 cup red wine vinegar for 30 minutes to decrease sharpness. Tear lettuce into bite sized pieces. Toss lettuce with all but 3 tablespoons of the pine nuts, scallions, 1/2 of cheese, 1/2 of prosciutto, and all of basil.

Making the dressing:

In a medium skillet, slowly cook the garlic in the olive oil over low heat for about 8 minutes, until garlic barely colored. Remove garlic with slotted spoon and reserve. Turn to medium-high heat and add vinegars. Cook a few moments until acid is diffused slightly. Add brown sugar to taste & bubble slowly for 1 minute. Taste for sweet/tart balance and adjust with more balsamic vinegar or sugar to taste. If too sharp, let boil for a few minutes. Stir in reserved garlic and season with salt and pepper.

To serve:

Top with drained onion and scatter rest of pine nuts, cheese, and prosciutto over the salad. Reheat the dressing, stir vigorously to blend, and spoon over the salad. Serve immediately.