Line a 9x13 inch pan with aluminum foil or parchment paper and lightly spray with nonstick spray. Place 1 cup butter and chocolate chips in a large bowl. Set aside.
In a large saucepan combine sugar and evaporated milk. Bring to a boil over medium high heat stirring constantly for 10 minutes. Pour the sugar mixture over the chocolate chips and butter.
Using an electric mixer beat the mixture for 3 minutes. Mix in the vanilla.
Spread the chocolate into your 9x13 inch pan. Allow to completely cool before frosting.
To make the caramel cashew topping: In a microwave safe bowl, melt caramel and heavy cream 30 seconds at a time stirring until melted and smooth. Pour and spread evenly on top of the fudge. Top evenly with cashews and gently press into the caramel. Let completely cool. I liked to pop mine into the fridge for a bit right before cutting.