Original recipe here.

My adaptation: Makes about 60 cookies

Crust:
2 sticks (1 cup) unsalted butter, softened
6 ounces cream cheese, softened
3 cups all-purpose flour
1 teaspoon salt

Filling:
4 large egg
4 tablespoons butter, melted and cooled
3 cups firmly packed brown sugar
1 teaspoon vanilla

1 cup chopped walnuts

Make the crust: Cream the butter and cream cheese in bowl of electric mixer. Add salt and flour and beat until it forms a dough. Transfer to gallon-sized zippered plastic bag and press flat. Chill 30 minutes.

Make the filling: Whisk together eggs, brown sugar, melted butter, and vanilla. Keep covered; it thickens and dries up as it sits.

Preheat oven to 375°F.

Press 1 1/4-inch balls of the dough into each hollow of a 24-mini-muffin tin. I use the rounded end of a lemon reamer handle for this. You can either leave the edges crumbly, or do like I do and press them smooth with my fingers. Pour filling into crust, leaving room for walnuts. Sprinkle walnuts into filling. Bake ~15 minutes or until crusts are golden and just beginning to pull away from the sides of the tin. Cool in the pan on a rack, 10 minutes. Poke out with the flexible tip of a knife — plastic knives work here — or a small spatula. Let cool completely on racks. Store in airtight containers for a few days at room temperature, a couple of weeks in the fridge, or up to two months in the freezer.