Add half and half, butter, brown sugar and vanilla to a medium saucepan. Over low heat cook until sugar dissolves, stirring occasionally. Take off of the heat and add in the heavy cream. Refrigerate mixture for 2-4 hours or overnight. (This helps get the ice cream really cold before we freeze it)
Take chilled ice cream out of the refrigerator and add to your ice cream maker to churn. Follow manufactures instructions.
After the ice cream is done sprinkle in the homemade toffee and stir.
Homemade Toffee
Add brown sugar and butter to a small saucepan. Cook over low medium heat for 8-10 minutes whisking constantly. Continue to cook until a candy thermometer reaches 300 degrees. If the mixture is getting too brown turn down the heat.
Pour mixture onto a silicon baking sheet or greased parchment paper and allow to cool.
Once cooled break up the toffee into pieces and set aside. (I place them in a ziploc bag and use a mallet to crumble them up).