Rub the lemon juice into the sugar. Adding some citric acid to sugar results in inverting some of the sugar, which prevents crystallization and softens the finished product.
Add the sugar to a heavy-bottomed saucepan or sugar pot. Place the pot over high heat and constantly stir the sugar with a wooden spoon. Constant stirring is essential to achieve even heating of the sugar. Continue caramelizing the sugar mixture until amber color is achieved.
Remove caramelized sugar from the heat and add the glucose syrup and stir. Set aside to cool down a little.
Meanwhile, bring the cream to a boil. With the caramelized sugar mixture at low heat, slowly pour it into the hot cream, stirring, and ensuring that the sugar mixture is completely incorporated.
Stir in the pumpkin purée and 1 tsp of the gingerbread spice mix and return the cream mixture back to a boil, then slowly pour it over the chopped dark (or milk) chocolate. Let the chocolate rest for 1 minute and melt.
Stir the chocolate mixture with a mixing paddle or a spoon in vigorous small circles, starting in the center and moving outwards until the mixture emulsifies and all the chocolate melts. If you have difficulty getting all the chocolate to melt, set the pan over a hot water bath and mix until the remaining chocolate melts. While doing so, keep an eye on the temperature of the ganache and don't let it go above 90F (32C).
Finally, slowly pour in the brandy while stirring until it is evenly incorporated.
Pour the ganache into a large flat pan. You want the ganache to cover just the bottom of the pan in a thin layer. Cover with plastic wrap and let it cool down at room temperature until it reaches 77F (25C) or slightly lower. The consistency should be thick but fluid to fill the chocolate shells properly.
Using a disposable pastry bag (or simply a Ziploc bag) with a small opening cut in the tip, fill the chocolate shells to within 1/8" (3mm) of the tops.
Allow the ganache to crystallize at room temperature until the top is solid, for several hours of overnight.
Next seal the tops using the tempered dark chocolate. Let the tops crystallize at room temperature for several hours or overnight. Then refrigerate the filled molds until the chocolate pulls away from the inside of the molds, approximately 20 minutes.
Place a piece of stiff cardboard over each mold and invert the mold to release the finished chocolates.