Preheat oven to 350°F,
Place the pie crust in a pan. Make holes in the crust using a fork.
Add sour cream, granulated sugar, beaten egg, all-purpose flour, vanilla extract, and salt to the bowl.
Mix together. Add this sour cream mixture to the crust. Peel and core fresh pears.
Then, cut into 1/4" thick slices. Place them over the sour cream filling. Bake in the preheated oven for 15 minutes.
Add all-purpose flour, sugar, butter, and cinnamon to the small bowl. Mix together using a fork until crumbly.
Remove pear pie from the oven. Sprinkle the crumble topping over the pie.
Bake for additional 30-40 minutes or until pie is golden brown and filling is set.
Then, let it cool completely at room temperature. Then, cover with an aluminum foil or plastic wrap. Refrigerate before serving.