Prepare the shortcrust pastry: In a bowl, combine butter, flour, a pinch of salt, and fresh thyme. Knead the mixture, adding a little water to make the dough elastic. Wrap in cling film and let rest in the fridge for 30 minutes.
Prepare the asparagus: Trim the hard ends of the asparagus and slice the stems, leaving the tips longer. Heat a pan with a drizzle of olive oil, season asparagus with salt and pepper, and sauté for 5 minutes until crunchy. Separate the tips from the stems and let cool.
Make the filling: In a bowl, combine ricotta and mascarpone for a creamy texture. Add eggs, grated Parmesan, salt, pepper, and nutmeg. Mix in the cooked asparagus stems (not the tips). Add a little marjoram and mix well.
Assemble the pie: Roll out the shortcrust pastry between two sheets of baking paper to about 0.5 cm thickness. Transfer to a cake tin, trim the edges, and prick the base with a fork. Pour in the filling and smooth out.
Decorate and bake: Arrange the reserved asparagus tips randomly on top of the filling. Fold the excess pastry edges over the filling. Bake in a static oven at 180°C (356°F) for 30-35 minutes until golden and set.
Serve: Remove the pie from the oven, let cool slightly, slice, and serve as an appetizer.