Brown Sugar-Walnut Streusel

BROWN SUGAR-WALNUT STREUSEL
Adapted from Baking From My Home to Yours
10 tablespoons unsalted butter, at room temperature
1/2 cup sugar
2/3 cup (packed) light brown sugar
2/3 cup all-purpose flour
1/2 teaspoon salt
1 cup chopped walnuts
Put all the ingredients except the nuts in a food processor and pulse just until the mixture forms clumps and curds and holds together when pressed.  Scrape the topping into a bowl, stir in the nuts and press a piece of plastic wrap against the surface.  Refrigerate until needed.  Covered well, the crumb mixture can stay in the refrigerator for up to 3 days.
This is a little more than you need for the 7-x-11-inch breakfast cake … or not: my husband always says that there’s no such thing as too much streusel.