Prepare the Pancakes: In a medium bowl, whisk flour, baking powder, cinnamon, salt, baking soda, and pumpkin pie spice to combine. In a separate medium bowl, toss apples with brown sugar to evenly coat; let stand, stirring occasionally, until apples have released some liquid and broken down slightly, 20 to 30 minutes.

For the Apple Topping: While the apples macerate, melt butter in a medium saucepan over medium heat. Add apples, brown sugar, cinnamon, and pumpkin pie spice and cook, stirring frequently, until apples are tender and can be pierced easily with a knife, 10 to 15 minutes. Remove from heat and stir in maple syrup; set aside, covered, in a warm place.

For the Maple Whipped Cream: In a large bowl, combine heavy cream and maple syrup. Using an electric hand mixer, whip on medium speed until medium peaks form, about 2 minutes. Cover and refrigerate until ready to use. (Whipped cream can also be prepared in the bowl of a stand mixer fitted with a whisk attachment.)

Whisk egg, milk, sour cream, melted butter, and vanilla into macerated apple mixture until well combined. Add apple mixture to flour mixture; using a whisk or flexible spatula, stir just until combined. Set a wire rack inside a rimmed baking sheet; set aside.

Heat a large nonstick griddle to medium heat (350°F/175ºC) or large nonstick skillet over medium. Using a ⅓ cup scoop, scoop batter onto griddle or skillet to form pancakes. Spread into 4-inch discs spaced ½- to 1-inch apart. Cook until bubbles start to appear on top of batter and bottoms are golden brown, 2 to 4 minutes, adjusting heat as needed to prevent overbrowning. Carefully flip pancakes and cook until bottoms are lightly golden and pancakes are cooked through, 2 to 4 minutes. Transfer to prepared wire rack. Repeat with remaining batter.

Serve pancakes immediately; garnish with apple topping, chopped toasted pecans, maple syrup, and maple whipped cream.