Heat over, 350 degrees Fahrenheit (180 degrees Celsius)
Cream butter and sugar with a mixer.
Add eggs and vanilla. Beat for 5 minutes until light and fluffy.
In a separate bowl prepare dry mixture; Sift flower, baking powder, baking soda and salt.
Alternatively add dry ingredients and yogurt to creamed mixture. Don't overmix the batter, as not to take the air out of the dry mixture.
With a spatula, fold in apples.
Pour the batter into a greased round cake pan, spread evenly.
To make the caramel topping on the cake, in a small pan on the stovetop mix pecan, brown sugar, cinnamon and butter until crumbly. Sprinkle topping evenly over batter.
Place sliced apple on top of caramel topping in a circular design.
Bake for 45 minutes, or until cake is well done.