Carefully fill a large roasting pan with hot water to a depth of 2 inches; place on center rack of oven. Preheat oven to 350°F. Grease a 12 to 14 cup, light-colored Bundt pan.
Make the cake batter: Beat butter, brown sugar and granulated sugar in a bowl by hand or with a heavy-duty mixer on medium speed until fluffy (3 minutes). Add the egg and beat until blended. Sift together flour, spices, baking soda, baking powder and salt in another bowl.
In a separate bowl whisk together pumpkin, whole milk and vanilla. Add flour mixture to butter mixture, alternating with the pumpkin mixture. Start and end with flour mixture. Beat gently but firmly by hand or on low speed with mixer after each addition. The cake batter will be very thick.
Make the caramel: In a medium saucepan add a little water to the sugar, just enough to make it moist, 1 -3 tbsp. Swirl the water around to coat the sugar evenly. Over medium heat bring the sugar and water to a boil, with the pan covered. Making caramel can be daunting as it tends to crystallize into a solid mess but by keeping the saucepan covered you will create constant moisture inside the pan and this "dew effect" will prevent crystallization from happening. Lift the lid occasionally to check on the color of the caramel. We want it golden dark (not burned). Always be careful when handling hot caramel; it can burn you badly. Evenly distribute the caramel all over the bottom of a 12 - 14 cup Bundt cake pan. Let it cool down a bit.
Evenly spoon the cake batter, smoothing the top.
Make the flan mix: Place condensed milk, evaporated milk, cream cheese, eggs, and vanilla in a blender. Process on high speed until (30 seconds) and stop it to scrape sides if necessary. Pour flan mixture over batter in Bundt pan. Cover loosely with aluminum foil.
Carefully remove roasting pan with hot water from preheated oven. (The water should be steaming when removed from oven.) Place the covered pan inside roasting pan and return to oven. Bake at 350°F until a wooden pick inserted in center comes out clean, 1 hour and 40 minutes, rotating the pan halfway through bake time.
Remove Bundt pan from roasting pan. Place on a wire rack to cool until slightly warm, for 1 hour. Gently invert onto a large serving plate. Spoon the caramel from pan over top; sprinkle with pecans. Serve additional caramel. You can also top with whipped cream instead of caramel.