To make crust, heat oven to 350°. Combine cookie crumbs, butter, sugar, and salt in a large bowl and stir until mixture resembles wet sand. Firmly and evenly press about 1/3 cup mixture into each 4-inch tart pan. Bake until fragrant, about 15 minutes. Let cool completely while preparing filling.

To make filling, use an electric mixer to combine cream cheese, butter, and powdered sugar until light and fluffy, about 2 minutes. Add peanut butter, vanilla, and salt, and beat until smooth. Divide mixture evenly between tartlet pans and smooth tops.

To make ganache, combine chocolate and salt in a medium bowl. Bring cream to a simmer in a small saucepan and immediately pour over chocolate chips. Let sit for 2 minutes, then stir until smooth. Let cool for 5 minutes.

Pour about 3 tablespoons ganache over each tartlet and smooth with a spatula. Refrigerate until set, about 1 hour. Garnish with crushed peanuts before serving, if desired.