The spoon they’re talking about is a wooden spoon.
Before the days of the rotary beater, the typical way of creaming butter and sugar was with a wood spoon. The rough edges on the spoon make air pockets in the butter, making the creaming process faster. (Faster than using a metal spoon, that is.)
From the box of A.D. from Lutz, Florida, by way of Pennsylvania in the 1940s, and originating in Ohio in the 1920s.
1 cup butter
2 cups sugar
Cream butter with a spoon and add sugar gradually, beating thoroughly.
Add grated lemon rind and juice and then the well beaten egg yolks.
Stir in stiffly beaten egg whites and add sufficient flour that the dough may be kneaded. Roll thin and cut into hearts.