Add chocolate chips, coconut milk, sugar, and salt to a heavy saucepan, stir to combine.
Over low heat, stir until chocolate chips are completely melted.
Add vanilla and coconut oil, stir to incorporate. Spread fudge into a parchment-lined 8x8-inch pan.
Add peanut butter to the top, use a toothpick to swirl the peanut butter into the chocolate. Be careful not to over swirl, just enough to get the swirl effect.