Preheat oven to 350. Get a stick of butter out of the fridge to warm to room temperature.
Grease and lightly flour a loaf pan.
With a hand mixer cream together in a large bowl:
1/4 C butter (room temperature)
1 Cup granulated sugar
1 Cup yogurt (plain or vanilla is fine)
Beat in 1 Tablespoon of vanilla extract (I don't measure, I just pour a splash in)
Sieve into a smaller bowl:
1 and 2/3 Cups all purpose flour
2 teaspoons baking powder
1 and 1/2 teaspoons baking soda
Add the dry to the wet in two installments and beat until smooth and creamy (a couple minutes).
Put batter into prepared loaf pan. Bake for 40 minutes. Cool in the pan 20 minutes or so and then turn out onto a plate to continue cooling.
For more depth of flavor add a bit of cinnamon to the dry ingredients.
Alternatively, substitute another extract for some of the vanilla.
This cake is too light to carry heavy mix-ins, but would support a little bit of citrus zest.