Buttery Raspberry Streusel-Filled Coffee Cake

Set oven to 350 degrees.

Set oven rack to second-lowest position.

Grease a 13 x 9-inch baking pan, and line bottom with parchment paper to prevent bottom of cake from over-browning).

Mix together all streusel ingredients; set aside.

With an electric mixer, cream butter and sugar until fluffy, about 4-5 minutes, until no sugar granules remain.

Mix in eggs and vanilla; beat until blended, about 1-2 minutes, scraping bowl often.

Stir in the sour cream; beat until well blended, about 1 minute.

In a small bowl, sift together the flour, baking soda, baking powder and salt.

Add to the creamed mixture, beating until blended.

Gently fold in the raspberries or blueberries (if using) with a spatula, if you are using fresh berries, careful not to break the berries while mixing in, especially if using fresh raspberries.

Spoon about two-thirds of the cake batter into the prepared baking pan.

Sprinkle half of the streusel mixture on top.

Then dollup the remaining cake batter on top of the streusel mix (does not have to cover completely).

Then sprinkle the remaining streusel mixture on top.

Bake for about 1 hour, or until cake tests done.