Blend together the butter with the sugar and the vanilla, creaming thoroughly.

Blend in the flour gradually.

Divide the dough into 4 equal parts.

Into one part, add 4 drops of red food color, into a second part, add 4 drops of yellow food color and into a third part, add 4 drops of green, blending very well each color with your hands.

Leave the fourth part without food color.

With your hands, roll down each part of dough in very long strips of about 1/2-inch-thick, placing the strips one along the other, side-by-side on a floured table or board.

With a rolling pin, roll out lengthwise at 1/8-inch thick, making a four-color strip of about 3 inches wide.

Repeat until all the dough is transformed into rainbow strips.

With a round-shape cookie cutter, cut cookies, trying to get a pair number of cookies if you plan to fill them (sandwich style).

Place cookies on a greased baking sheet and cook 8 to 10 min in a preheated oven at 350°F Do not brown.

Let cool and fill with the peanut butter filling.

Peanut butter filling:

Place the brown sugar and the flour in a saucepan and add the water.

Cook over medium heat stirring constantly.

When thick, remove from heat and add the peanut butter, then let cool.

Use 1 teaspoon between each pair of cookies.