Preheat the oven to 350°F(177°C). Grease 8 ½ * 4 ½ inch (21,5*10,5cm) loaf pan and line the bottom and sides with parchment paper, about 2 inches(5 cm) of overhang on each side.
Place the flour (210 grams - 1 and ½ cup), baking powder and salt(optional) in a medium bowl and stir with a whisk. Set aside.
Put the sugar and eggs into a large bowl and stir with a whisk.
Stir in the melted butter, milk, and vanilla extract.
Pour the wet ingredients over the flour mixture and stir with a whisk until combined.
Place the raspberries into a medium bowl and add 1 tablespoon of flour (you can use the bowl that you used for the flour mixture) and shake the bowl a couple of times to let flour cover all the raspberries. If the raspberries are too big, you can cut them into two before adding the flour to avoid them sinking to the bottom once baked.
Add the white chocolate and raspberries into the batter and gently fold with spoon/spatula.
Spoon the batter into a loaf pan. When you spoon it instead of pouring, you can see how well raspberries are distributed.
Bake for almost 55 minutes or until the toothpick inserted into the center comes out clean.
Let the cake cool in the pan for an hour and then let it cool on a wire rack.