01 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
02 - Combine chopped dates and boiling water in a small bowl. Stir in baking soda and let sit for 10 minutes to soften.
03 - Cream butter, dark brown sugar, and granulated sugar in a large bowl until light and fluffy.
04 - Beat in egg and vanilla extract until fully combined.
05 - Whisk together flour, baking powder, and salt in a separate bowl.
06 - Add dry ingredients to wet mixture and mix just until combined.
07 - Fold in softened date mixture including all liquid until evenly distributed throughout dough.
08 - Drop tablespoon-sized scoops onto prepared baking sheets, spacing 2 inches apart.
09 - Bake for 10 to 12 minutes until edges are set and centers appear slightly underbaked. Cool on pan for 5 minutes, then transfer to wire rack.
10 - Melt butter and brown sugar in small saucepan over medium heat, stirring until dissolved. Add heavy cream and salt, bring to simmer, and cook 1 to 2 minutes until thickened. Remove from heat and stir in vanilla.
11 - Drizzle warm toffee glaze over cooled cookies. Allow glaze to set before serving.