Preheat the oven to 350°F (175°C).
Prepare the crust: In a mixing bowl, cream together the softened butter, sugar, and molasses until smooth.
Add the pinch of salt, ground ginger, ground cinnamon, and 1 extra-large egg; mix until combined.
Stir in 1.5 cups of flour gradually until a dough forms.
Press the dough evenly into the bottom and up the sides of a 9-inch pie pan.
Bake the crust for 12-15 minutes until lightly golden. Remove from oven and let cool slightly.
While crust is baking, prepare the filling: In a bowl, whisk together the egg yolks, sweetened condensed milk, Key lime juice, 2 tablespoons flour, and vanilla extract until smooth and well combined.
Pour the filling into the warm crust and bake for an additional 12-15 minutes, or until the filling is set but slightly jiggly in the center.
Remove the pie from the oven and allow it to cool at room temperature for 30 minutes.
Refrigerate for at least 3 hours, preferably overnight, before serving to let the flavors meld and the filling fully set.
Slice and enjoy this zesty and warmly spiced Key Lime Pie!