Preheat your oven to 350°F (175°C) and prepare a 9x5-inch loaf pan. Lightly grease it and sprinkle with flour.

In a large mixing bowl, combine the all-purpose flour, both sugars, baking soda, and optional salt. Whisk until evenly distributed.

In a separate bowl, melt the unsalted butter then whisk together with the egg, buttermilk, canola oil, and vanilla extract.

Pour the wet ingredients into the dry mixture and mix gently until just combined; a few lumps are okay.

Coat the raspberries with flour to prevent sinking, then fold them gently into the batter.

Transfer the batter to the prepared loaf pan and bake for 45 minutes to 1 hour, until a toothpick comes out clean.

Let the bread cool in the pan for 15 minutes, then transfer to a wire rack to cool completely before slicing.