Preheat oven to 350°F (175°C). Grease a fluted tube (Bundt) pan with the softened butter.
In a mixing bowl, cream together sugar, 1 cup butter, and cream cheese until light and fluffy, about 3 minutes.
Mix in vanilla extract and salt until combined.
Add eggs one at a time, beating well after each addition.
Gradually add flour, one cup at a time, mixing until just incorporated.
Fold in muddled strawberries gently.
Pour batter into prepared pan and sprinkle with vanilla sugar.
Bake for about 1 hour, or until a toothpick inserted into the center comes out clean.
Cool in pan for 5–10 minutes, then invert onto a wire rack and cool completely.