Preheat the oven to 350°F. Butter and flour a bundt cake pan.
Cream together butter and sugar until fluffy. Add eggs one at a time, beating well after each.
Sift together flour, baking soda, baking powder, and spices, then stir into batter.
Stir in yogurt and vanilla until well combined and no white streaks remain. The batter will be very thick. Fold in pears.
Spoon into the bundt pan. Bake 40-50 minutes, or until a toothpick inserted into the cake comes out clean. Let cake cool 10 minutes in the pan, then invert onto a wire rack to cool completely.
To make the topping, combine butter, dark brown sugar, and cream in a small saucepan over medium heat and melt, stirring. Once melted, increase slightly and bring to a full rolling boil for 1 minute.
Remove from heat and whisk in vanilla (be careful, as the caramel will bubble up). Add sifted powdered sugar and whisk until completely incorporated and smooth. Whisk in salt to taste. Let cool slightly, then pour over the cake. The topping will firm up as it cools.
Notes
Glaze minimally adapted from the Hungry Housewife.