In a bowl, stir together the graham cracker crumbs, cinnamon (if using), packed brown sugar, and sea salt together.
Pour in the melted butter and stir well.
Add the crumbs to your springform pan or your pie tin.
Press in the sides, then the edges, then the bottom. Use the bottom and/or sides of a lightly greased cup. to ensure the crumbs are tightly pressed in.
This crust does not need to be baked, and will do well just being frozen for a few minutes. If your recipe calls for a baked crust, follow the instructions for that recipe.
Notes
Press in the crumbs in the order recommended so you are sure you have sturdy sides and edges to hold up your filling.