Since much of the appeal of these see-through wafers is in their brittle, caramelized texture, make them on a dry day.
Have all ingredients at room temperature, 68┬░ to 70┬░F. Position a rack in the upper third of the oven. Preheat the oven to 350┬░F. Grease cookie sheets or cover with well-greased aluminum foil.
Toast, stirring constantly, in a baking pan until very lightly browned, 5 to 6 minutes:
1/2 cup finely chopped pecans
Set aside to cool. Increase the oven temperature to 375┬░F.
Melt in a medium saucepan over medium heat:
10 tablespoons unsalted butter
Adjust the heat and boil the butter gently, stirring occasionally, until the solids on the bottom of the pan turn light brown, 3 to 4 minutes. Remove from the heat and stir in until well blended:
1 cup packed light brown sugar
1/4 cup light corn syrup
1 tablespoon milk
1/4 teaspoon salt
Stir in until well combined:
1 1/2 cups old-fashioned rolled oats
2 tablespoons all-purpose flour
2 teaspoons vanilla
Stir in the nuts. Drop the batter by scant measuring teaspoonfuls onto the sheets, spacing about 3 inches apart. DonΓÇÖt crowd, as the wafers will spread a great deal. The batter will stiffen as it cools. Bake, 1 sheet at a time, until the cookies are golden brown all over and slightly darker at the edges, 6 to 8 minutes; rotate the sheet halfway through baking for even browning. Remove the sheet to a rack and let stand until the cookies firm slightly, about 1 minute. Gently transfer the cookies to racks to cool. If they become too cool and brittle to be removed easily, return them to the oven a minute to soften.
