Place the butter in a light colored skillet or saucepan over medium-high heat until melted. Continue cooking, swirling the pan constantly or stirring with a heatproof rubber spatula, until the butter is dark golden brown and has a mesmerizing nutty aroma. Transfer to a small bowl, and allow to cool until lukewarm but still liquid. I'd recommend browning the butter called for the frosting immediately after this one, since it needs more time to solidify.

Adjust oven rack to middle position, and preheat the oven to 350F/180C. Line 2 muffin pans with 14 cupcake liners in total.

In a large bowl, whisk together the flour, baking powder, salt, baking soda, cinnamon, nutmeg, ginger and set aside.

In another medium bowl, combine together the pumpkin puree, buttermilk, vanilla and set aside.

In the bowl of a stand mixer fitted with the whisk attachment (or handheld mixer), beat together both sugars and eggs on medium speed until light and fluffy, almost doubled in volume and is cappuccino colored, about 5 minutes.

With the machine running, slowly drizzle in the melted brown butter down the side of the bowl. Continue beating until fully incorporated.

On low speed, add one third of the flour mixture, followed by half of the pumpkin mixture, then another third of the flour mixture, followed by the remaining pumpkin mixture and ending with the flour mixture, scraping the bowl as needed. Mix just until combined. Do not overbeat the batter.

Use an ice cream scoop to divide the batter evenly among the 14 cupcake liners.

Bake until the cupcake's center springs back when lightly touched and a toothpick inserted in the center comes out clean or with a few moist crumbs attached, about 17 minutes.

Let cool in the pan for about 5 minutes then transfer to a wire rack to cool completely before filling and frosting.

While the cupcakes bake, make the cinnamon toffee sauce.

In a saucepan, melt the butter, brown sugar, cream and salt together over medium heat, stirring constantly with a whisk. Bring to boil and simmer for about 1 minute, stirring constantly.

Remove from the heat and stir in the cinnamon. Let cool to room temperature before pouring over the cake. While the sauce is cooling, prepare the Brown Butter Cream Cheese Frosting.

Cut a cone from the top of each cupcake. Insert the tip of a paring knife at a 45-degree angle about 3/4 inch from the edge of the cupcake, making sure not to pierce the bottom. Cut out and remove the cake cone. An apple corer would also work perfectly here, but it will make less room for sauce. Cut off all but the top 1/4 inch of the cone, leaving a circular disc of cake, which will be used later to 'plug' the filled hole. Discard (better yet, eat!) the bottom of the cone.

Using a small spoon, squeeze bottle or a piping bag with the corner snipped off, pour in the cooled sauce into each cupcake. Be generous and fill almost to the top.

Use the reserved cake 'plug' to cover the tops of the cupcakes, where they have been filled.

Using your favorite piping tip (I used an Ateco 867 tip) or an offset spatula to frost the cupcakes with the Brown Butter Cream Cheese Frosting. The way it's done here, is by starting to pipe in the center, going around once, then ending with a swift pull.

If desired, drizzle with leftover toffee sauce, then top with pumpkin spice toffee shards, if using.

Store cupcakes in an airtight container until serving. Keep leftovers in the fridge for up to 3 days, bringing them to room temperature before serving.