Preheat oven to 350°F (177°C). Lightly grease the bottoms and sides of eight 4-inch tart pans with removable bottoms. Place greased tart shells onto a baking sheet.
In a food processor fitted with the metal blade, process the 4½ cups of pretzels until the texture is like coarse sand (see Chef’s Tips). Remove 1¼ cups (150 g) of the pretzel crumbs. Either place the measured amount into a separate bowl or remove the excess crumbs (if there are any) from the food processor and place the measured amount back into the food processor bowl.
Add in the Redpath® Dark Brown Sugar, mixing or pulsing a few times to evenly distribute the sugar throughout the crumbs. Drizzle in the melted butter and mix until the crumbs resemble wet sand (see Chef’s Tips). Divide the mixture (approximately ¼ cup / 35 grams of the pretzel mixture in each shell) evenly amongst the prepared tart shells.
Press the crumbs evenly up the sides of the shell, and then with a flat-bottomed cup (e.g. ¼ cup measuring cup), press the crumbs evenly into the bottom of the tin. Repeat process with the remaining tart shells. Place the baking sheet with the tart shells into the fridge to chill and resolidify the butter; 10 minutes.
Place the baking sheet into the preheated oven and bake for 8 to 10 minutes or until tart shells are fragrant and lightly browned. Remove from the oven and place on a wire cooling rack to cool completely.
In a heavy-bottomed saucepan, preferably nonstick, combine butter, the Redpath® Dark Brown Sugar, and lemon juice. Place over medium heat and cook while continuously stirring with a heat-proof spatula until butter and brown sugar is completely melted. Reduce heat to medium-low and continue to stir until mixture begins to darken in colour; about 3 minutes.
Pour in the condensed milk. Bring to a boil while continuously stirring mixture over medium-low heat to prevent mixture from separating (see Chef’s Tips). Cook for 1 to 2 minutes or just until mixture thickens and coats the back of a spoon. Do not overcook, or the toffee layer will become too hard to slice when completely cooled.
Remove from heat and stir in the vanilla extract and salt. Set aside to cool slightly, stirring every so often to prevent a skin from forming; 10 minutes.
Equally divide the warm toffee into the completely cooled pie crusts; about 3 to 4 tablespoons per tart. If necessary, use a small offset spatula to smooth the surfaces. Place the baking sheet with the filled tart shells into the fridge to chill while preparing the topping.
With a sharp knife, slice bananas into rounds, about ⅛- to ¼-inch thick.
In a large, chilled bowl, add the cold, heavy cream. Using a hand mixer (see Chef’s Tips), whip the cream on low speed just until it begins to thicken. Increase speed to medium and whip to soft peaks.
Sift in the Redpath® Icing Sugar and milk powder (if using), and add the vanilla extract. Whip mixture on medium-high speed until stiff peaks form; do not overmix.
Layer banana slices over the chilled toffee layer of each mini pie. Pipe or dollop the whipped cream over the banana slices, ensuring the banana slices are completely covered, if they have not been tossed in lemon juice, to prevent bananas from oxidizing and turning brown.
Place into the fridge to chill completely; at least 2 hours or overnight to allow flavours to meld and the filling to completely set.
Serve as is, or garnish the whipped cream with a sprinkling of grated chocolate or chocolate curls, or dust the tops with cinnamon or cocoa powder. Store any leftover pielets in an airtight container in the fridge for up to 5 days.
*Approximately 4½ cups of pretzels are needed to get 1¼ cup (150 grams) of crushed pretzels needed for the crust.
*If a food processor is not available, place pretzels into a large resealable bag. Place a kitchen towel over the bag to prevent punctures and use a rubber mallet or rolling pin to crush the pretzels into crumbs. The finer the crumb, the more readily the crust will hold its shape; do not crush pretzels to a powder.
*If the resulting pretzel mixture is dry (does not resemble wet sand), add an additional tablespoon of melted butter to the mix and pulse to moisten until the desired consistency is reached. Alternatively, add additional crushed pretzels to the mixture if it is too wet and sticky to handle.
*Do not increase heat when making the toffee layer. Heating the ingredients too quickly can result in the butter separating from the caramel. If this happens, remove from heat and use a whisk to quickly blend the mixture back into an emulsion. Reduce temperature before placing back onto the heat.
*Choose bananas that are ripe but free from any dark spots. Bananas for this pie should be firm and not mushy. If planning on not fully covering the banana layer with the whipped cream, toss the sliced bananas with about 1 or 2 teaspoons (5 to 10 ml) of lemon juice to prevent bananas from turning brown before assembling.
*To ensure the heavy cream whips up, chill the bowl and whisk attachments for at least 15 minutes before using. Use heavy cream that is just taken out from the fridge for optimal results.
*Milk powder is used in the heavy cream to help further stabilize it, although it is not necessary.
*Redpath® Golden Yellow Sugar can be used in place of the Redpath® Dark Brown Sugar though the resulting pielets will have a less pronounced caramel-toffee flavour and will be lighter in colour.