Preheat oven to 350 degrees F.
In a medium bowl, combine the oats, flour, sugar, almonds, butter and vanilla. Mix until well combined.
Spray a 9 inch tart pan with cooking spray. Press the crust mixture on the sides and bottom of the pan. Bake for 20 minutes until lightly browned. Cool completely.
Start on the filling. In a small pot, bring the half and half and sugar to a simmer until the sugar is dissolved. Once warm, reduce heat to medium and whisk in the egg yolk and continue to whisk for 2-3 minutes until smooth. Add flour and pinch of salt and stir to combine. Lastly, add the butter and almond extract and stir to combine, remove from heat.
Transfer the pastry cream into a bowl and chill for 30 minutes. Once chilled, pour the pastry cream into the chilled tart shell. Arrange banana slices on top and drizzle with the melted chocolate and sprinkle with the slivered almonds