How to Make It
Preheat oven to 350°F. Coat a 10-inch cast-iron skillet (or cake pan) with nonstick spray. Using an electric mixer, beat butter, brown sugar, granulated sugar, and vanilla in a medium bowl on medium-high speed until light and fluffy, 3 to 5 minutes. Beat in pumpkin until evenly incorporated.
Whisk together flour, salt, pumpkin pie spice, and baking soda in a bowl; add to butter mixture and beat on low speed until just combined, about 1 minute. Beat in ¾ cup each of the chocolate and toffee pieces.
Spread batter in prepared skillet and smooth top with spatula. Sprinkle remaining ¼ cup each chocolate and toffee over top. Bake until set in the middle and browned around the edge, 30 to 35 minutes. Cool in pan 20 minutes.
Cut cookie into 8 wedges, and serve warm or at room temperature with vanilla ice cream.