Begin by preparing the crust in a 9-inch springform pan. Crush 1¼ cups (175g) of graham crackers into fine crumbs using a plastic bag and a rolling pin or mallet.
Melt ¼ cup (65g) of salted butter and combine it thoroughly with the cracker crumbs until the mixture resembles wet sand. Press this mixture firmly and evenly over the bottom and up the sides of your prepared springform pan, creating an even layer. This forms the sturdy foundation for your pie and should be compacted well to prevent it from crumbling when sliced.
For the toffee filling, melt ½ cup (115g) of salted butter in a nonstick pan over medium heat, then add ½ cup + 2 tbsps (115g) of light muscovado sugar. Stir this mixture constantly until the sugar has fully dissolved and the butter has absorbed the molasses notes from the sugar.
Once combined, add both 14-ounce (397g) cans of full-fat condensed milk to the pan and continue stirring constantly for approximately 5 minutes, watching carefully as the mixture transforms into a thick, golden toffee.
Pour this hot toffee mixture directly onto the cooled crust and allow it to cool completely and set at room temperature or in the refrigerator.
Once the toffee layer has set, prepare the topping by slicing 3 bananas and immediately tossing the slices in a little fresh lemon juice to prevent browning. Layer the banana slices evenly over the toffee filling.
Lightly whip 1¼ cups (300ml) of heavy cream to soft peaks and spread it gently over the bananas, creating a smooth, creamy layer. Finish with a light sprinkling of grated Belgian milk or dark chocolate over the top. Remove the springform sides carefully and serve immediately for the best texture and flavor.
