Brown Butter and Walnut Tuile Cups

These little cookie cups were really yummy. You have to work very quickly to get the cup shape, but they are worth the effort. They would be great with some caramel ice cream and chocolate sauce! If you have a silpat mat, it would be a lot easier to use than the parchment. As much as I love parchment, it was hard to work with in this particular recipe.
7 T. unsalted butter
2 large egg whites
½ C. sugar
Pinch of salt
½ t. vanilla extract
2/3 C. minus 1 T. flour
¼ C. finely chopped walnuts
Position rack in center of oven and preheat to 350 F. Line 2 large rimmed baking sheets with parchment paper. Arrange four ¾-cup custard cups upside down on work surface. Stir butter in saucepan over medium heat until nutty brown and milk solids are dark brown, 6 to 7 minutes. Carefully pour browned butter into small bowl and cool slightly. Combine egg whites, sugar, and salt in medium bowl; whisk until moisture is foamy, about 1 minute. Add warm browned butter, leaving dark brown milk solids behind in bowl; whisk until blended. Whisk in vanilla. Add flour and whisk until blended and smooth. Crop batter by scant tablespoonfuls onto prepared baking sheets, spacing 4 inches apart. Using small offset spatula, spread each to 5 inch round. Sprinkle generous ¼ teaspoon finely chopped walnuts over each. Bake tuiles, until evenly golden all over, about 11 minutes. Working quickly and using wide metal spatula, carefully lift each tuile from sheet and immediately drape over custard up and press to mold to cup, making cookie bowls. Cool until tuiles are set. Carefully remove tuiles from cups and place on rack to cool completely. Repeat procedure with batter and walnuts on cool baking sheets, making total of 12 cookies bowls.