In a skillet, brown the diced bacon over medium-high heat.
Pat it dry with paper towel.
Set aside.
Wash and dry the skillet.
Heat 30 ml (2 tbsp) of olive oil and the butter over medium heat.
Add the onion.
Sauté the onions for about 15 minutes, stirring frequently, until caramelized.
Set aside.
In a bowl, mix together 30 ml (2 tbsp) of olive oil and herbes de Provence.
Set aside.
Flour the countertop.
With a rolling pin, roll out 1 of the balls of dough in a 45 x 30 cm (18 x 12 in.) rectangle.
Brush with half of the oil and herb mixture. Sprinkle with 60 ml (4 tbsp) of grated Parmesan. Spread with half of the caramelized onions. Sprinkle with half of the goat cheese.
Season with pepper.
Layer in this order: 250 ml (1 cup) of arugula, 80 ml (1/3 cup) of diced bacon and 250 ml (1 cup) of mozzarella.
Roll up the dough lengthwise and loosely to obtain a 45 cm (18 in.) long Stromboli.
Fold up the ends.
With the tip of a knife, score 4 slits on the top to allow steam to escape.
Brush with olive oil and sprinkle with 15 ml (1 tbsp) of Parmesan.
Repeat the previous steps for the second Stromboli.
Place the Stromboli on a baking sheet lined with parchment paper.
Bake in the oven for 20 minutes.
Remove from the oven and let cool for about 10 minutes.