½ cup (115 grams) unsalted butter (room temperature)
Preheat oven to 350*F/177*C. Grease 9×5 inch (23x13 cm) loaf pan with butter (or use cooking spray), then line with parchment, first with a sheet covering the long side of the pan, then with a sheet covering the short side of the pan, with about an inch or two of overhang on all sides. Grease the top of the parchment with butter.
In a food processor, pulse the raspberries and 2 tablespoons (30 grams) of sugar to make a puree. Set aside.
Whisk the flour, baking powder, and salt in a medium bowl, set aside.
Cream butter and 1 ¼ cups (280 grams) sugar on medium speed until light and fluffy, about 4-5 minutes, scraping down the bowl as necessary. Add eggs, one at a time until blended, then add vanilla.
Reduce speed to low and add the flour in 3 batches, alternating with the sour cream, beginning and ending with the flour. Be careful not to overmix. With a spatula, scrape the batter off the sides and bottom of the bowl and fold to mix.
Place half of the batter in the loaf pan and dot with ½ cup (118 mL) of the raspberry puree. Add the remaining batter and puree. Use a knife to marble the puree.
Bake for 1 ¼ hours or until an inserted toothpick or cake tester comes out clean. Cool in the pan on a wire rack for 30 minutes, then remove to serving platter to cool completely before cutting.