Preheat oven to 325º F and lay your crust out in a standard pie dish. Bake for 10-12 minutes, or until just lightly browned.
Remove from oven and set aside.
In a medium saucepan over medium heat, melt 4 tablespoons butter and heavy cream together until butter is melted, then whisk in cornstarch and sugar, stirring continuously until thickened. 6-7 minutes.
Stir in maple syrup, maple extract, vanilla extract and salt, if using, and whisk until incorporated.
Pour filling into pie crust, then drizzle remaining (melted) butter over the top.
Whisk together remaining topping ingredients, sugar and cinnamon, and sprinkle over filling.
Place baking dish in oven and bake for 25-30 minutes, or until crust is golden brown and filling is bubbly. Center should be set, but still a little wobbly.
Remove from oven and let cool, then refrigerate until set. 2-3 hours.