Gluten-Free Blueberry Cake (Dairy-Free)

Name: Gluten-Free Blueberry Cake (Dairy-Free)
Prep time: 1 h
Cook time: 30 min
Total time: 1 h 30 min
Cuisine: American
Ingredients: 4 ½ cups (500g) fresh or frozen blueberries; 1 tablespoon lemon juice; 1 tablespoon granulated sugar; pinch of fine sea salt; ⅔ cup (151g) dairy-free salted butter, room temperature; 1 ½ cups (300g) granulated sugar; 2 tablespoons canola or vegetable oil; 2 large eggs, room temperature *can sub liquid egg replacer for vegan; 1 teaspoon vanilla extract; 1 ¾ cup (280g) gluten-free flour blend *check to see if it contains xanthan or guar gum; 2 teaspoons baking powder; 1 teaspoon fine sea salt; ½ teaspoon xanthan gum *omit if gf blend contains it or if using regular cake flour; ½ cup (117ml) blueberry reduction, room temperature; ¼ cup (59ml) dairy-free milk, room temperature; optional: extra blueberries for decor; optional: fresh or dried flowers for decor; 2 cups (480g) dairy-free salted butter, room temperature; 5 ½ cups (660g) icing sugar; ¼ cup (59ml) blueberry reduction; 2 teaspoons lemon juice