For streusel: In a medium bowl, whisk collectively flour, sugar, salt, and cinnamon. Utilizing 2 forks or your fingers, reduce in chilly butter till combination is crumbly; stir in pecans. Refrigerate till prepared to make use of.
Preheat oven to 350°F (180°C). Spray a 9-inch spherical cake pan with baking spray with flour.
For cake: Within the bowl of a stand mixer fitted with the paddle attachment, beat butter and sugar at medium pace till fluffy, 3 to 4 minutes, stopping to scrape sides of bowl. Add eggs, one by one, beating nicely after every addition. Beat in vanilla.
In a medium bowl, whisk collectively flour, baking powder, and salt. With mixer on low pace, regularly add flour combination to butter combination alternately with buttermilk, starting and ending with flour combination, beating simply till mixed after every addition.
In a small bowl, stir collectively raspberry unfold and three tablespoons (54 grams) batter.
Unfold about 1½ cups (404 grams) remaining plain batter into ready pan. Gently unfold raspberry batter onto batter in pan, leaving a ½-inch border alongside edges. Place remaining plain batter (about 1 cup or 269 grams) right into a pastry bag. Pipe on high of raspberry batter. Utilizing an offset spatula, rigorously unfold plain batter to edges of pan. (It’s OK if raspberry isn’t fully lined.) Sprinkle with streusel.
Bake till a picket decide inserted in middle comes out clear, about 50 minutes. Let cool in pan for 10 minutes. Take away from pan, and let cool on a wire rack for half-hour. Greatest served heat. Retailer in an hermetic container for as much as 3 days.
