For the Strawberry butter - whip the butter until soft and fluffy. Then add in powdered sugar, jam, and fresh strawberries that have been diced and partially crushed. Mix together well. Store in an airtight container in the refrigerator.
Preheat oven to 375 degrees. Grease a popover pan or muffin tin. Combine flour and salt in a medium sized mixing bowl. Set aside.
Beat the eggs in a mixing bowl until frothy. Heat the milk in the microwave until warm. (be sure it's not hot, just warm)
Then add the warm milk to the beaten eggs and beat together until combined.
Then add the flour/salt mixture to the egg and milk mixture and beat or whisk until combined.
Add to the prepared muffin tin filling 2/3 full.
For the muffin tin you may want to fill every other cup so that they don't connect together as they grow when cooking. Don't open the oven door during baking because it will cause the popovers to deflate.
Bake just until golden brown, about 25 to 35 minutes. They will feel dry to the touch and sound hollow when you tap on them. (my pans were dark so the popovers cooked fast)
After the popovers come out of the oven, pierce the bottom with a knife to let the steam escape.
Serve immediately with strawberry butter.