For the macarons, beat egg whites with lemon juice until very stiff peaks form. Gradually sprinkle in sugar. Continue beating until glossy and cut resistant. Fold in almonds gently.
Place mixture into a piping bag with a large round spout. Pipe small circles measuring about 2 cm (approximately 1 inch) onto a baking sheet lined with parchment paper. Bake in a preheated oven at 130°C (approximately 250°F) for about 40 minutes, leaving the oven door slightly open.
For the filling, mix jam with powdered sugar until smooth. Spread over half of the macarons and top with remaining half, pressing together gently. Dry and serve.