INGREDIENTS
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6 oz butter, at room temperature
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4.75 oz (2/3 cup) granulated sugar
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5 oz (2/3 cup packed) brown sugar
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2 eggs, at room temperature
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2 tsp vanilla extract
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8 oz (1 cup) buttermilk, at room temperature
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4 oz (1/2 cup) sour cream, at room temperature
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2 tbsp water or brewed coffee
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7.8 oz (1 3/4 cups) all-purpose flour
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3 oz (1 cup) sifted unsweetened cocoa powder
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1 1/2 tsp baking soda
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1/2 tsp salt
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8 oz unsweetened chocolate, finely chopped
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6 cups (24 oz) powdered sugar
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2 sticks (8 oz) unsalted butter, at room temperature
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6 tbsp milk, plus more if necessary
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2 tsp vanilla extract (can sub other extracts)
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1/4 tsp salt
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12 oz chopped semi-sweet chocolate
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12 oz heavy cream
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5 oz (2 1/2 cup) miniature marshmallows
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6.5 oz (1 3/4 cup) toasted walnuts, coarsely chopped