In a heavy pot on high heat, add oil and one kernel of popcorn. Cover. When kernel pops, add the rest. Pop until you know longer hear the popping sounds.
Remove from heat and spread on a baking sheet. In the same pot, melt butter over medium heat and add toffee and peanuts. Stir until toffee melts, adding more butter, if needed. Pour over popcorn. Melt chocolate in a small saucepan or in the microwave and drizzle over the top of the popcorn. Let sit for a few minutes then serve.