Preparing the Tartlet Shells

1. Preheat the Oven: Preheat your oven to 375°F (190°C).
2. Mix the Dough: In a large bowl, combine the all-purpose flour and salt. Add the chilled, cubed butter and use a pastry cutter or your fingers to mix until the mixture resembles coarse crumbs.
3. Add Water: Gradually add ice water, one tablespoon at a time, mixing until the dough comes together in a ball. Be careful not to overwork the dough.
4. Chill the Dough: Wrap the dough in plastic wrap and refrigerate for about 30 minutes to allow it to firm up.
5. Roll and Cut: On a lightly floured surface, roll out the dough to about 1/8-inch thickness. Using a round cutter, cut out circles and press them into tartlet molds or a muffin tin.
6. Bake the Shells: Place a small piece of parchment paper in each tartlet and fill with pie weights or dried beans. Bake for 10 minutes, then remove weights and parchment and bake for an additional 5 minutes until lightly golden. Set aside to cool.

Preparing the Filling

1. Cook the Spinach: In a skillet over medium heat, sauté the chopped spinach until wilted. Remove from heat and let cool slightly.
2. Mix the Filling: In a mixing bowl, combine the cream cheese, heavy cream, Parmesan cheese, lemon juice, Dijon mustard, garlic powder, cayenne pepper, salt, and pepper. Stir until smooth.
3. Combine Ingredients: Gently fold in the wilted spinach and lump crab meat until well combined.

Assembling and Baking the Tartlets

1. Fill the Shells: Spoon the crab-spinach mixture into the prepared tartlet shells, filling each one generously.
2. Bake: Place the filled tartlets on a baking sheet and bake in the preheated oven for 15-20 minutes, or until the filling is set and slightly golden on top.
3. Cool and Serve: Allow the tartlets to cool slightly before removing them from the molds. Serve warm or at room temperature.