Preheat oven to 350°. Spray a 12-well mini fluted muffin pan* with baking spray with flour. Place 3 peach slices in each prepared well.
In the bowl of a stand mixer fitted with the paddle attachment, beat together butter and 1 cup sugar at medium speed until light and fluffy, 3 to 4 minutes, stopping to scrape sides of bowl. Add eggs, one at a time, beating well with each addition. Add vanilla bean paste, beating until incorporated.
In a medium bowl, whisk together flour, baking powder, and ground ginger. With mixer at low speed, gradually add flour mixture to butter mixture alternately with milk, beginning and ending with flour mixture, beating just until combined with each addition. Fold in crystallized ginger.
Spoon batter over peaches, filling each well three-fourths full. Spoon 1 teaspoon blackberry preserves in center of batter in each well.
Bake until a wooden pick inserted in centers comes out clean, approximately 25 minutes. Let cool in pan for 10 minutes. Carefully remove cakes, and let cool completely on a wire rack.
Place Blackberry Frosting in a piping bag fitted with a small star tip (Ateco #822). Pipe a small rosette on top of each cake.
In a medium bowl, toss together blackberries and remaining 1 cup sugar until fully coated. Place a sugared blackberry on top of each cake. Serve immediately, or refrigerate in an airtight container until ready to serve.
Recipe by TeaTime Magazine at https://teatimemagazine.com/peach-blackberry-puddings/