Preheat oven to 350°. Spray a 9-inch round cake pan with baking spray with flour. Line bottom of pan with parchment paper.
In a large bowl, beat together butter and sugar with a mixer at medium speed until fluffy, 2 to 3 minutes, stopping to scrape sides of bowl. Add eggs, one at a time, beating well after each addition. Add sweet potato, vanilla extract, and rum extract, beating until combined.
In a medium bowl, whisk together flour, baking powder, pumpkin pie spice, and salt. With mixer at low speed, gradually add flour mixture to butter mixture, beating just until combined. Spoon batter into prepared pan, smoothing top with an of set spatula.
Bake until a wooden pick inserted in center comes out clean, 40 to 45 minutes. Let cool in pan for 10 minutes. Remove from pan, and let cool completely on a wire rack.
Using a serrated knife, trim domed top from cake. Using a 2-inch round cutter, cut 9 rounds from cake.
Place Spiced Meringue Topping in a piping bag fitted with a large star tip (Wilton #2D). Pipe Spiced Meringue Topping onto tops of cake rounds. Using a kitchen torch, lightly brown meringue.
Garnish with gold luster dust, if desired. Serve immediately, or store at room temperature in an airtight container for up to 2 hours.
Recipe by TeaTime Magazine at https://teatimemagazine.com/sweet-potato-cakes-with-toasted-meringue/