Preheat oven to 400°F (200°C).

Grease a 12-cup muffin pan.

Cream butter in a mixing bowl.

Gradually add sugar to the creamed butter and beat well with an electric mixer until light and fluffy.

Add eggs, one at a time, beating after each addition until well combined.

Stir in sour cream and vanilla extract until evenly distributed.

In a separate bowl, combine flour, baking soda, salt, and poppy seeds.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Be careful not to overmix.

Spoon the batter into the prepared muffin pan, filling each cup about 2/3 full.

Bake for 20 minutes, or until the muffins are golden brown and a toothpick inserted into the center comes out clean.

Remove the muffins from the pan immediately and let them cool on a wire rack.