Preheat oven to 350 degrees. Butter a standard 12-cup (each 2 1/2 inches wide) muffin pan; set aside. In a large bowl, whisk together flour, baking soda, and salt; set aside.
With an electric mixer, cream butter and sugar until light and fluffy. Add eggs and vanilla; beat until combined. Add flour mixture, and beat just until combined (do not overmix). Fold in chopped toffee.
Divide batter among prepared cups, filling each about halfway. Bake until golden brown and a toothpick inserted in the center of a cupcake comes out clean, 18 to 22 minutes.
Transfer to wire rack; cool 10 minutes in pan. Turn out blondies onto rack; cool completely, top side up.