Preheat oven to 350°F.
In large bowl, combine flour and sugar. Cut in butter until mixture is crumbly. Remove 1 cup of the mixture and set aside.
To remaining crumb mixture add baking powder, soda, salt, sour cream, 1 egg and vanilla. Beat until combined, batter will be thick. Spoon mixture into greased muffin cups. Make a small indentation in the batter.
Combine cream cheese, 1/3 cup sugar and remaining egg. Spoon cream cheese mixture evenly over batter. Spoon raspberry preserves over cream cheese mixture. Add nuts, if using, to reserved crumb mixture and sprinkle over muffin tops.
Bake muffins 20-24 minutes.
This recipe makes 15 standard-sized muffins. If using larger or smaller sized tins baking time will need to be adjusted.
If you only have one muffin tin with 12 muffin cups, you can also cram all the ingredients into the 12 standard-sized tins, but be sure to grease the entire muffin pan, including the tops so the baked muffins will not stick. They will puff up and spread, and need about 8-10 more minutes baking time. You will probably want to omit the nuts as there won't be room for them
Another option is to make the 12 standard muffins and use the remaining batter, filling and topping in one of the small-size foil loaf pans, making a little raspberry cream cheese coffee cake! Bake alongside the muffin tins, but allow an extra 8-10 minutes of baking time for the loaf.