Melt the butter in a saucepan.

Gradually add the flour to the melted butter, mixing continuously until a smooth roux forms.

Slowly pour in the beef stock, stirring constantly to avoid lumps.

Cook the mixture for 10 minutes, stirring occasionally to prevent sticking, until thickened.

In a separate saucepan, heat the olive oil.

Add the finely chopped onion and diced carrots to the heated oil.

Sauté the vegetables until they soften.

Add the ground beef to the sautéed vegetables.

Season the meat with ground nutmeg, salt, and pepper.

Cook the beef until it is browned, breaking it up with a spoon.

Transfer the cooked meat mixture to the saucepan containing the broth mixture.

Stir in the chopped parsley and lemon juice.

Cook for an additional minute to combine the flavors.

Pour the mixture into a bowl.

Allow the mixture to cool completely.

Divide the cooled meat mixture into 4 equal portions.

Shape each portion into an oblong shape.

Roll each oblong in toasted breadcrumbs, ensuring it is fully coated.

Dip each breadcrumb-coated oblong into the egg wash, making sure it is evenly covered.

Roll each egg-washed oblong in breadcrumbs again, creating a double coating.

Heat oil in a frying pan over medium heat.

Carefully place the meat patties into the hot oil.

Fry the patties until they are golden brown on all sides.

Remove the fried kroketten from the pan and place them on a paper towel-lined plate to drain excess oil.

Serve hot.