Heat oven to 350 degrees. Tightly wrap the outside of the springform pan with an oven bag and tie on the side if possible. Then, tightly wrap the outside with two layers of aluminum foil, making sure the foil goes all the way up the side for extra insurance. Start boiling water for the water bath.
To make the cheesecake filling, combine the softened cream cheese and dark brown sugar in the large mixing bowl. Using a stand mixer with the paddle attachment or a hand mixer, beat on medium speed until smooth, creamy and fluffy, about two to three minutes. As needed, scrape down the side of the bowl with a spatula.
Beat in the sour cream, vanilla and salt until it all comes together. Don't overmix.
Beat in the eggs one at a time on medium speed. Mix just until the egg is fully incorporated before adding the next. Gently stir in toffee bits.
Pour half of the cheesecake batter into the crust and dollop with half of the bananas foster curd. Use a butter knife to swirl around the batter. Repeat with the remaining cheesecake batter and curd.
Place the wrapped springform pan into a large roasting pan. Fill with enough boiling water to come about halfway up the side of the springform pan. Don’t pour water past the foil. Alternatively, you can place a pan of boiling water on the rack below the cheesecake. I recommend this method if you don’t have an oven bag and are worried about leakage.
Place the cheesecake on the middle rack, close the oven door and immediately turn the oven to 250 degrees. Bake for 1 hour and 40 minutes.
After the hour and 30 minutes, turn off the oven completely. Do not open the oven door. Let the cheesecake sit for 3 hours. Do not open the oven door at this point either.
Remove the cheesecake and allow to come to room temperature, about an hour or so. Place in the refrigerator uncovered with the springform pan intact. Do not cover at this point or condensation will build up. Refrigerate until the cheesecake is cold, at least four hours, before covering. Allow to set in the refrigerator for at least another four hours or overnight, which is preferred.
When ready to serve, remove the springform pan. The parchment paper should make it easy to remove. If desired, garnish with banana slices and whipped cream. Enjoy!