Banana Pastry Cream
1 cup milk
5 tablespoons sugar
3 large egg yolks
2 tablespoons cornstarch
1 teaspoon vanilla extract
1 small banana, ripe (you can use from 1/2 to all of the banana, depending on size and how much banana flavor you want)
1 tablespoon lemon juice
1 1/2 cups all purpose flour
1/2 cup confectioner's sugar
1/4 teaspoon salt
9 tablespoons (4 1/2 ounces) very cold unsalted butter, cut into cubes
1 large egg yolk
4 ounces dark (62%-70%) chocolate, roughly chopped
1/2 cup heavy cream
2 bananas, ripe
1/2 cup heavy whipping cream
For the banana pastry cream:
Combine 3/4 cup milk and 3 tablespoons of sugar in a saucepan. Heat just until the milk starts to bubble at the edges.
Meanwhille, whisk the remaining sugar and the egg yolks together in a medium bowl. Whisk the cornstarch and remaining milk together in another bowl and add to the egg yolk mixture.
When the milk has started to bubble, pour it in a steady stream into the egg yolk mixture, whisking constantly to prevent the eggs from scrambling.
Pour the mixture back into the saucepan and return to the stove, cooking over medium heat and whisking constantly, until it thickens and comes to a boil. Stir in vanilla and remove from heat.
Let pastry cream cool while you cut up the banana. Puree with the lemon juice in a food processor until smooth.
Fold the banana puree into the pastry cream. You can now press a piece of plastic wrap to the surface of the cream and place in the refrigerator to chill.
For the tart shells:
Combine flour, confectioner's sugar, and salt in bowl of a food processor and combine.
Add in cold butter and process until pea-sized lumps of dough form - do not overprocess into a ball of dough. It should be loose and crumbly.
Add in egg yolk and process until dough starts to come together. Turn the dough out of the bowl onto a work surface and lightly press together into a ball - if it's too loose, you can process a little more, but don't do too much - you want to work this dough as little as possible to have a light and crumbly texture.
Butter one 9-inch tart pan or six 5-inch tart pans - ones with removable bottoms work best. Carefully press the dough into the pans, working it over the bottom and up the sides. Again, try not to overwork the dough - press gently and work as quickly as possible.
Chill shells in freezer for about 15 minutes.
Meanwhile, preheat oven to 375 degrees F.
Usually recipes for these tart doughs involve lining the shells with pie weights. If you like doing this or have fears of burning your shells, go ahead. However, I've never had issues with just baking the shells as is - I check them halfway through and if the shells are puffing up too much I just press them down with a dough tamper or wooden spoon.
Bake shells for 15 minutes, then rotate and bake another 10-18 minutes until they are golden brown and fully baked.
Let cool on wire rack before filling.
For the ganache:
Place chocolate in a medium bowl.
Heat cream in saucepan on stove over medium heat until the edges start to bubble.
Pour cream over chocolate and let stand for a minute. Stir with a wooden spoon to combine the two into a smooth mixture.
Spread a layer of ganache on the bottom of each tart shell and let cool and set. It doesn't have to set all the way, but it should be slightly firm to avoid mixing with the pastry cream.
Cut the bananas into thin slices, about 1/4" thick, and spread in a layer over the ganache.
Remove the pastry cream from the refrigerator and beat or stir with a spoon to loosen it up.
Whip the cream in a stand mixer until soft peaks form.
Fold the whipped cream gently into the pastry cream until fully incorporated.
Spread the banana pastry cream into the shells and smooth the surfaces with an offset spatula.
Chill in the refrigerator for about 20 minutes to set before serving. You can decorate the top with chocolate curls if you like.