Prepare the crust: Place your pie crust into a 9–10 inch pie pan and set aside.
Make the syrup: In a saucepan, combine the water, sugar, and cream of tartar. Bring to a boil and cook for about 5 minutes, stirring until sugar dissolves. Remove from heat and stir in lemon juice, zest, and cinnamon.
Assemble the filling: Break 60 Ritz crackers into bite-sized pieces and layer them evenly in the prepared pie crust. Pour the hot syrup mixture over the crackers, ensuring everything is coated.
Prepare topping: In a small bowl, combine the crushed Ritz crackers, melted butter, brown sugar, cinnamon, and nutmeg. Mix until crumbly.
Bake the pie: Sprinkle the topping evenly over the pie. Bake at 425°F (220°C) for about 15 minutes, then reduce heat to 375°F (190°C) and bake another 15–20 minutes, until the topping is golden and the pie is bubbling.
Cool and serve: Allow the pie to cool slightly before serving. The texture and aroma will be shockingly close to a traditional apple pie.