Rhubarb Cookies recipe from Mountain View Country Market in Chuckey,TennesseeRhubarb Cookies

1 2/3 cups all-purpose flour
3/4 teaspoon kosher salt
1/2 teaspoon baking powder
1/2 teaspoon baking soda
1 1/4 sticks (10 tablespoons) unsalted butter, at room temperature
2/3 cup packed light brown sugar
1 large egg plus 1 large yolk
1 teaspoon pure vanilla extract
1 cup white chocolate chips (about 6 ounces)
1 cup walnut halves (about 4 ounces), roughly chopped
1 1/2 stalks rhubarb (about 4 ounces), chopped into 1/4-inch pieces
1 tablespoon flaky sea salt

Sift the flour, kosher salt, baking powder and baking soda together in a large bowl. Beat the butter and brown sugar in a large bowl with an electric mixer (or using a stand mixer fitter with the paddle attachment) on medium-high speed until light and fluffy, about 3 minutes. Beat in the egg and yolk, then beat in the vanilla. Reduce the mixer speed to low. Add the dry ingredients and beat until well combined, about 1 minute. Fold in the chocolate chips and walnuts, then fold in the rhubarb. Cover the bowl with a clean dish towel and refrigerate the dough for at least 1 hour or up to overnight. Preheat the oven to 375 degrees F. Line 2 baking sheets with reusable nonstick mats (or parchment). Use a 1-ounce ice cream scoop to scoop the dough onto the prepared baking sheets, spacing about 2 inches apart (you should have about 10 cookies, roughly 1 1/2 ounces each, per baking sheet). Sprinkle the sea salt on top of the dough balls. Bake, rotating the baking sheets from top to bottom and front to back halfway through, until the cookies are golden around the edges but still soft in the middle, 14 to 16 minutes. Let cookies cool for 10 minutes on the baking sheets, then transfer to a wire rack to cool completely, about 30 minutes. Store the cookies in a tightly sealed container at room temperature for up to 5 days.