Cut the butter into pieces and mix together with the molasses and sugar in a saucepan. Heat the saucepan while stirring until the sugar has dissolved. Pour the mixure into a large mixing bowl and let cool. Add the almonds, 400 grams (approximately 14 ounces) of flour, the spices, the baking soda and the egg. With the dough hook of a hand mixer, thoroughly knead. You might need to add a little more flour. Pour the mixture into a small bowl and mix in the rum. Knead the batter until it no longer sticks and shines.
Cover the bowl with a plastic wrap and let rest in the refrigerator overnight.
Preheat the oven to 180°C (approximately 350°F). Line a baking sheet with parchment paper.
Roll out the batter onto a floured surface until 3-4 mm (approximately 1/6 of an inch) thick and cut out bear shapes. Place the cookies on the baking sheet and bake in the oven for about 15 minutes. Remove the cookies from the baking sheet carefully and let cool.
Mix the powedered sugar with the lemon juice until smooth and fill in a piping bag. Decorate the bears, let the decoration dry and serve.