Preheat oven to 400 degrees F
Place the pie crust into a 9 inch pie pan
In a large saucepan add the water, sugar and cream of tartar
Bring to a boil on medium-high heat
Add crackers and simmer on medium-low for 5 minutes, stirring just once or twice gently
Fill your pie crust with half the mixture and lay a few more crackers on top of the filling. Cover with the rest of the filling.
Sprinkle the cinnamon and lemon juice over the top
Make the topping by combining the topping ingredients into a bowl and stirring to combine
Sprinkle over the top of the filling
Bake for 10 minutes at 400 degrees F
Reduce oven to 350 degrees and cover edges of pie crust with foil
Bake 20 more minutes
Remove from the oven and cool to set up