Preheat the oven to 350 degrees. Mix crust ingredients and press into a 9-inch pie plate. Bake at 350 for 10 minutes.
In a heavy-bottomed saucepan, melt butter and brown sugar over low to medium heat. Set a timer for 5 minutes; heat gently while stirring continuously. It might lightly bubble, but you don’t want to full-blown boil it. This is to caramelize and develop the flavor.
Add sweetened condensed milk; stir or whisk to incorporate. Bring it up to a gentle boil; stir or whisk continuously for 3-4 minutes (I always set a timer for this – you don’t want to overcook it). The color will start darken into a medium brown and the consistency will thicken slightly.
Pour the toffee into the cooled crust – it should be thickened, but still smooth and pourable. Let it rest on the counter for 1-2 hours until the toffee is cooled and dry to the touch. (If it seems like it might be too loose or runny, you can pop it in the fridge for a few hours until it’s set.)
Using an electric mixer, whip the heavy cream with the sugar and vanilla until medium peaks form.
When the top is set, arrange sliced bananas on top in a single layer. Add whipped cream; spread it to cover. Top the whole thing with chocolate shavings!
You can serve this immediately at room temperature, or pop it in the fridge for a few hours to chill. (If it’s in the fridge, give it 15-30 minutes of rest on the counter before serving to soften!)
