Hermit Slices

Preheat oven to 350°. Line a 13x9x2" baking dish with 2 layers of parchment paper or foil, leaving a generous overhang on long sides. Lightly coat with nonstick spray.

Whisk flour, cinnamon, salt, baking soda, ginger, and nutmeg in a medium bowl.

Using an electric mixer on medium-high speed, beat brown sugar and 10 Tbsp. butter in a large bowl, scraping down sides occasionally, until pale and fluffy, about 4 minutes. Add egg and continue to beat, scraping down sides once or twice, until incorporated and smooth, about 2 minutes. Add molasses and vanilla and beat until combined. Add dry ingredients and mix on low speed until just blended. Add walnuts and raisins and mix with a large spoon until no spots of flour remain.

Transfer dough to prepared baking dish, spreading evenly across bottom. Bake until top springs back slightly and is slightly darker and edges are firm, 20–30 minutes.

Meanwhile, melt remaining 1 Tbsp. butter in a small saucepan over medium heat. Cook, swirling occasionally, until butter foams, then browns, about 4 minutes. Whisk in powdered sugar and 1 Tbsp. water to form a smooth glaze. Brush over hermits and let cool completely. Using parchment overhang, carefully remove hermits and cut into 3½x1½" bars.

Do Ahead: Hermits, without glaze, can be made 2 months ahead; store airtight and freeze.