Preheat your oven to 350°F (175°C). Thoroughly grease and flour a 10-12 cup Bundt pan, ensuring all nooks and crannies are coated to prevent sticking.

In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.

In a large mixing bowl, cream together the softened butter and granulated sugar with an electric mixer on medium-high speed until light and fluffy, about 3-5 minutes.

Add the eggs one at a time, beating well after each addition until fully incorporated. Scrape down the sides of the bowl as needed.

Stir in the lemon zest and vanilla extract until combined.

In a separate small bowl, combine the lemon juice and buttermilk.

With the mixer on low speed, gradually add the dry ingredients to the wet ingredients in three additions, alternating with the buttermilk mixture in two additions, beginning and ending with the dry ingredients. Mix just until combined; do not overmix.

Gently fold in the fresh raspberries by hand, being careful not to crush them too much.

In a small saucepan, combine the raspberries, granulated sugar, and lemon juice.

Cook over medium heat, stirring frequently, until the raspberries break down and the mixture thickens slightly, about 5-7 minutes. Mash any larger pieces of raspberry with a spoon. Remove from heat and let cool slightly.

Pour about half of the cake batter into the prepared Bundt pan.

Drizzle spoonfuls of the raspberry swirl mixture over the batter in the pan. Use a knife or skewer to gently swirl it into the batter, being careful not to drag it to the bottom of the pan.

Carefully spoon the remaining cake batter over the raspberry swirl layer, spreading it evenly to cover.

Bake for 55-65 minutes, or until a wooden skewer inserted into the center of the cake comes out with moist crumbs, not wet batter.

Remove the cake from the oven and let it cool in the pan on a wire rack for 10-15 minutes.

Carefully invert the Bundt cake onto the wire rack to cool completely before glazing, at least 1-2 hours.

Once the cake is completely cool, prepare the lemon glaze. In a small bowl, whisk together the sifted powdered sugar and 3 tablespoons of fresh lemon juice until smooth. If the glaze is too thick, add more lemon juice 1/2 teaspoon at a time until desired consistency. If too thin, add more powdered sugar.

Drizzle the lemon glaze evenly over the cooled Bundt cake, allowing it to drip down the sides.

Let the glaze set for about 15-20 minutes before slicing and serving.