Polenta Shortcake with Blackberry Compote

Name: Polenta Shortcake with Blackberry Compote
Ingredients: 2 cup (300 grams) blackberries; 1/4 cup (50 grams) sugar; Juice of 1 lemon; Zest of 1 lemon; 1 pinch salt; 1 cup (125 grams) all-purpose flour; 2/3 cup (110 grams) instant polenta; 1 teaspoon (4 grams) salt; 2 1/4 teaspoon (8 grams) baking powder; 3 tablespoon (40 grams) granulated sugar; 1 1/4 cup (303 grams) heavy cream, plus more for brushing; Maldon salt, for sprinkling; Turbinado sugar, for sprinkling; 2 1/2 cup Corn Cream (https://food52.com/recipes/33124-corn-cream)