Prepare your pie crust dough using the recipe on my blog. Preheat oven to 350°F. Roll the dough on a lightly floured surface. You will need it to be 2 inches wider than your 9-inch tart pan with removable bottom. Gently place in pan, pressing down and up the edges. Remove any overlap, reserving dough. Set aside.
For the filling
In a large bowl, whisk together all of the pie filling ingredients until smooth. Pour into tart crust. (Note: you will have a little extra filling which you can bake in a muffin pan with the extra pie dough, if desired. It will take less time to bake than the tart.) Bake for 70 minutes. Let cool. Refrigerate for 8 hours or overnight.
For the pecan toffee
Cook light brown sugar and 4 tablespoons butter in a small skillet over medium, stirring constantly, until bubbly. Add pecans and cook, stirring constantly, 2 minutes or until golden. Pour mixture onto lightly greased (with cooking spray) parchment paper; cool completely. Break into pieces.
For the whipped cream
Beat heavy cream and ¼ teaspoon pumpkin pie spice at medium-high speed with an electric mixer until foamy; gradually add powdered sugar, beating until soft peaks form. Top chilled tart with whipped cream, sprinkle with toffee.