Grease and flour an 8.5 x 4.5-inch loaf pan. Preheat the oven to 350°F.
Prep the raspberries by washing them and then patting them dry. If they are large cut them in half for better dispersal in the quick bread. Place them in a small bowl.
Measure out all the ingredients. Measure 2 tablespoons of flour in a small bowl. This flour will be combined with the raspberries in a later step. Place the remaining flour, baking powder, baking soda, and kosher salt in a medium sized bowl and whisk for 30 seconds to combine.
Place the vegetable oil, sugar and eggs in a large bowl and whisk for 1-1/2 to 2 minutes to combine and partially dissolve the sugar. Add the prune puree and whisk until thoroughly combined.
Add the buttermilk and whisk to combine. Toss the raspberries with the reserved flour. Add the flour mixture and the raspberries to the wet ingredients. Use a large spatula to gently fold the dry ingredients and the raspberries into the wet ingredients by stirring from the bottom.
The batter will still be lumpy. Scrape the batter into the prepared loaf pan. Even out the batter but it doesn’t need to be perfectly smooth. Sprinkle the turbinado sugar across the top.
Bake for 55 to 65 minutes until the center is done of the temperature in the center is 202°F.
Remove the quick bread from the oven and let it cool in the pan for 10 minutes. Use a metal spatula to make the bread is loose from the sides and then gently turn it out onto a cooling rack and set it right side up. Let the cake cool for at least 45 minutes before slicing it.