Cream the softened butter and sugar together until smooth.
Add the almond flour.
Mix everything together, gradually adding the beaten egg little by little as you go.
Mix without whisking; otherwise, the almond cream will puff up during baking.
Wrap the almond cream in the bowl with plastic wrap or transfer it to a piping bag. Ideally, refrigerate it for an hour before using it. However, you can use it immediately if needed.
To use, fill a pre-baked tart shell that has been blind-baked halfway. For a Bourdaloue or Amandine tart, the almond cream is piped into a raw tart shell, and the entire tart is baked together. See the method demonstrated in the strawberry tart recipe.