You can create a recipe with foods that are saved in your Journal. Ticking the box to select foods and then click Create recipe.
On the New recipe page you can now name your recipe in the Title field. Then select the number of servings you want by default. You can also set the serving size for each ingredient. Finally, click the green Create recipe button.
Make sure you get the name, default servings and ingredient serving sizes right because you cannot modify the recipe in any way afterwards.