Sourdough Bread

12 T unsalted butter, 2.5 cups chopped onion, 3 green apples, cored and chunked but not peeled,

10 T butter, divided, 1 cup of celery, chopped, 1 cup leeks, chopped (just the white parts),

1 shallot, peeled and chopped into 3 or 4 pieces, 3 cloves garlic, 2 generous handfuls of basil