Sticky Toffee Date Cake

Name: Sticky Toffee Date Cake
Ingredients: Nonstick vegetable oil spray; 2 cups all-purpose flour, plus more for pan; 1½ cups (packed) dark brown sugar; 1½ tsp. baking powder; 1 tsp. ground cinnamon; 1 tsp. kosher salt; ½ tsp. baking soda; 1 cup (2 sticks) unsalted butter, cut into pieces, room temperature; 1 cup sour cream; 1 tsp. vanilla extract; 3 large eggs; 6 oz. Medjool dates, pitted, coarsely chopped; ¾ cup (packed) dark brown sugar; ½ cup (1 stick) unsalted butter; ¾ cup sour cream, plus more for serving; 1½ tsp. flaky sea salt, plus more; 2 oz. Medjool dates, pitted, torn; A 10-cup Bundt pan