In a large bowl, whisk together the flour, baking powder, cinnamon, cardamon, and nutmeg.
In the bowl of an electric mixer fitted with the paddle attachment or beaters, beat the avocado oil, butter, salt, and the sugars until combined, about 3 minutes.
Add the egg, peach schnapps, and vanilla and beat on low speed until well combined. Gradually add the flour mixture, alternating with the buttermilk, and beat on low speed until just combined, don't over mix! (The batter will be thick).
Transfer the batter to the prepared pan and smooth the top with a spatula. Arrange the peaches on the top, skin side up in a circular pattern so that they mostly cover the batter, and sprinkle the streusel topping.
Bake the plum cake for 50 to 60 minutes, until golden on top and a tester come out clean. Let cool in the pan on a wire rack. Cut into wedges and serve!