Preheat oven to 350 degrees F.
Grease 2 9-in round baking pans well. Don't worry about lining them with parchment paper. I tested lining one baking pan and buttering the other, and both cakes came out perfectly.
Toast the chopped pecans on a dry skillet over medium heat until fragrant. Set aside.
For the caramel sauce, in a medium saucepan over low heat, combine brown sugar, butter, heavy cream, and salt. Cook and stir over low heat until sugar is dissolved, and butter is melted. Remove half of the caramel and divide between the two greased cake pans. Sprinkle 3/4 cup of the toasted pecans between both pans. Cook the remaining caramel for about 5 min more until thickened. This will be to drizzle on your cake. Set aside.
For the cake, beat together eggs, sugar, and oil in a large bowl. (I used my stand mixer with whisk attachment) Add pumpkin and vanilla and mix. Combine flour, baking powder, baking soda, salt, and pumpkin pie spice. Gradually add to the pumpkin mixture and mix until combined. Don't overmix.
Spoon the batter evenly over the caramel sauce between the cake pans. Bake for 30-40 min until golden brown and a toothpick inserted in the center comes out clean. Cool for 5 min, then remove cake-side-down on a wire rack to cool completely.
For the whipped cream, beat heavy cream, powdered sugar and vanilla until stiff peaks form.
To assemble, place one cake, praline side up, on your serving plate. Spread with a generous amount of whipped cream, leaving 1-in space on the sides. Place the second cake layer on top and spread/pipe with remaining whipped cream and sprinkle with pecans. See notes* Drizzle with your remaining salted caramel sauce or drizzle each piece individually.