Melt the 3 tablespoons of butter in a frying pan on medium heat. Once the butter is melted, add the water and 1/2 cup brown sugar. Cook, stirring frequently, until the sugar has completely melted. Add the sliced pears and cook for another 2-3 minutes. Set aside.
Preheat oven to 350 degrees. Spray three 8-inch round pans with nonstick spray, line the bottom with parchment paper, and spray again. Set aside.
In a medium bowl, whisk together the flour, baking powder and salt. Set aside.
In a small bowl, mix together the buttermilk, honey and vanilla. Set aside.
In the bowl of a stand mixer fitted with the paddle attachment, beat the butter and sugar on medium speed until fluffy, about 4 minutes.
Add eggs, one at a time, beating well after each addition and scraping down the sides of the bowl as needed.
Gradually add in the dry and wet ingredients, alternating between the two, starting and ending with the dry ingredients. Mix until just combined.
In two of the pans, evenly place the pears on the parchment paper. Pour 2 tablespoons of the caramel sauce over the pears in each pan.
Evenly divide the batter between the three cake pans (about 16 to 17 ounces in each), being careful to gently spread the batter over the pears.
Bake for 30 minutes, until toothpick inserted into the center comes out clean.
Let cool in pans for 5-10 minutes, then remove to wire rack to finish cooling.
Reserve the leftover "caramel sauce." Once the cakes are cooled, drizzle the remaining sauce over the top of the cake layer that doesn't have pears.