Make cookie dough: In a large bowl, cream together the softened butter and granulated sugar until light and fluffy. Beat in the egg and vanilla extract.
Combine dry ingredients: In a separate bowl, whisk together the flour, baking powder, and salt. Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Do not overmix.
Chill dough: Cover the dough and refrigerate for at least 30 minutes, or until it's easier to handle.
Preheat oven: Preheat oven to 375°F (190°C). Grease a mini muffin tin.
Shape cookie cups: Scoop about 2 tablespoons of dough and press it into each muffin cup, forming a cup shape. You can use your fingers or the back of a measuring spoon to press the dough against the sides and bottom of the muffin cup.
Bake: Bake for 12-15 minutes, or until the edges are golden brown. Let the cookie cups cool in the muffin tin for a few minutes before transferring them to a wire rack to cool completely.
Make filling: While the cookie cups are cooling, prepare the filling. In a medium bowl, combine the drained ricotta cheese and powdered sugar. Beat until smooth and creamy. Stir in the mini chocolate chips, candied fruit (if using), pistachios (if using), and vanilla extract.
Chill filling: Cover the bowl and refrigerate for at least 2 hours to allow the filling to thicken.
Assemble cookie cups: Once the cookie cups and filling have cooled and chilled, spoon the ricotta cheese filling into each cookie cup.
Serve: Serve the Cannoli Cookie Cups immediately or store them in the refrigerator until ready to serve.