Mating: Pastel, butter, ghost female x normal male. This is a three gene pair problem.

Female:
gene pair 1 = pastel gene and normal gene (the pastel gene is codominant to the normal gene)
gene pair 2 = butter gene and normal gene (the pastel gene is codominant to the normal gene)
gene pair 3 = two ghost genes (the ghost gene is recessive the to normal gene)


Male:
gene pair 1 = two normal genes
gene pair 2 = two normal genes
gene pair 3 = two normal genes

Determine number of types of gametes.

Female gene pair 1 produces two (2) types of gametes (pastel and normal).
Female gene pair 2 produces two (2) types of gametes (butter and normal).
Female gene pair 2 produces one (1) type of gamete (all are normal).
Total number of gamete types = number from gene pair 1 * number from gene pair 2 * number from gene pair 3 = 2 * 2 * 1 = 4

Total number of female gametes using checkerboard. Gamete types from gene pair 1 across the top, and gamete types from gene pair 2 down the left side.

.......| pastel .......| normal
--------------------------------------------------
butter | pastel-butter | normal-butter
--------------------------------------------------
normal | pastel-normal | normal-normal
--------------------------------------------------

Make a new checkerboard with gamete types for gene pair 3 at the top and the results of gene pairs 1 and 2 down the side. This produces four gamete types:
pastel-butter-ghost
pastel-normal-ghost
normal-butter-ghost
normal-normal-ghost

Male gene pair 1 produces one (1) type of gamete (normal).
Male gene pair 2 produces one (1) type of gamete (normal).
Male gene pair 3 produces one (1) type of gamete (normal).
Total number of gamete types = number from gene pair 1 * number from gene pair 2 * number from gene pair 3 = 1 * 1 * 1 = 1. The male produces only one type of gamete--normal-normal-normal

Number of boxes in Punnett square = number of female gamete types * number of male gamete types = 4 * 1 = 4.

Punnett square has male gametes at the top and female gametes down the side.

....................| normal-normal-normal
--------------------|------------------------------------------------------
pastel-butter-ghost | pastel/normal butter/normal normal/ghost
--------------------|------------------------------------------------------
pastel-normal-ghost | pastel/normal normal/normal normal/ghost
--------------------|------------------------------------------------------
normal-butter-ghost | normal/normal butter/normal normal/ghost
--------------------|------------------------------------------------------
normal-normal-ghost | normal/normal normal/normal normal/ghost
--------------------|------------------------------------------------------

Convert genotypes to phenotypes:
Genotype pastel/normal butter/normal normal/ghost produces phenotype pastel butter (het ghost).
Genotype pastel/normal normal/normal normal/ghost produces phenotype pastel (het ghost).
Genotype normal/normal butter/normal normal/ghost produces phenotype butter (het ghost).
Genotype normal/normal normal/normal normal/ghost produces phenotype normal (het ghost).

See https://en.wikipedia.org/wiki/Punnett_square for how to do a Punnett square with more complex genotypes in the parents and with the forkline method.