Line a small sheet pan with parchment paper and set aside for a moment.
In a small saucepan over medium heat, melt butter. Add sugar and salt and whisk well to incorporate. Cook toffee over medium heat, stirring constantly until toffee is thick and reaches 300F on a candy thermometer, about 8-10 minutes.
Remove toffee from heat and immediately pour into prepared pan. Allow to cool completely at room temperature 1 hour.
Remove toffee from pan and break into bite-size pieces with a rolling pin. Set aside.
Ice Cream
Pour heavy cream into a large bowl or the bowl of a stand mixer fitted with a whip attachment. Use a handheld mixer or stand mixer to beat whipping cream on high speed until heavy cream forms stiff peaks.
In a separate bowl, whisk sweetened condensed milk, espresso, and vanilla until smooth. Gently fold in whipped cream.
Scrape ice cream mixture into a 9x5 loaf pan. Cover ice cream with plastic wrap and freeze 4 hours.
Remove ice cream from freezer and fold in toffee bits (ice cream should be semi-frozen) Return ice cream to freezer and freeze an additional 4 hours until firm. Enjoy!
Notes
Storing InstructionsStore ice cream in freezer up to 1 month.