Blackberry & Brie Mini Pizzas

INGREDIENTS

3/4 tsp

active dry yeast

3/4 cup

tepid water (about 80 degrees)

1 tbsp

olive oil

1 cup

unbleached all-purpose flour

The sponge

1 cup

unbleached all-purpose flour (plus 2 tablespoons if needed)

1 1/2 tsp

table salt

2 tbsp

unsalted butter

large onion (sliced)

1 tbsp

extra virgin olive oil

8 oz

Brie cheese (trimmed of outer rim)

1/2 cup

chopped walnuts

6 oz

fresh blackberries (large berries cut in half)

2 cups

fresh arugula

2 tsp

balsamic vinegar

salt and fresh ground pepper