Preheat the oven to 400°F (200°C). Line a baking sheet with a Silpat or parchment paper.
In a small bowl, mix 1 cup ricotta, 1 tablespoon chopped parsley, grated Parmesan to taste, a pinch or two of kosher salt, and several turns of freshly ground black pepper. Taste and adjust seasoning as needed.
Spoon about 1 teaspoon of the ricotta mixture into the center of a wonton wrapper. Roll the wrapper into a tight tube and place seam-side down on the prepared baking sheet. Repeat with remaining filling and wrappers.
Lightly brush each roll with olive oil, then bake for 10–12 minutes until the edges are crispy and the centers puff up.
To serve, spoon tomato sauce onto plates, top with the baked mini cannelloni, scatter parsley leaves and shaved Parmesan over them, and finish with freshly ground black pepper.